5. Mus Musculus.
Mus Musculus, Auctorum.
Of this species, there are six specimens in Mr. Darwin’s collection; two were found “living in the short grass, near the summit of the Island of Ascension, where the climate is temperate.”—D. Two others were procured “on a small, stony, and arid island, near Porto Praya, the capital of St. Jago, in the Cape de Verde Islands,—climate very hot and dry. Excepting during the rainy season, which is of short duration, these little animals can never taste fresh water, nor does the island afford any succulent plant.”—D. A specimen was also procured “on a grassy cliff, on East Falkland Island, at the distance of a mile from any habitation. It is singular that so delicate an animal should be able to subsist under the cold, and extremely humid climate, of the Falkland Islands, and on its unproductive soil.”—D. These specimens are all of them rather less than full grown individuals of the same species procured in England; in other respects, they do not differ.
The sixth specimen, which is from Maldonado, is considerably less than British specimens of the common mouse, and is of a richer and brighter colour, the head is smaller, the muzzle shorter in proportion, whilst the tarsi are even longer than in a large specimen of M. Musculus. These points of dissimilarity induced me to believe it was a distinct species, and to apply to it the specific name of brevirostris.[[17]] Upon re-examination, with the advantage of more experience, and consequently a better knowledge of the characters of these animals, I have changed my opinion. The teeth indicate that it is not an adult specimen, and agree perfectly with those of M. Musculus, both in form and size. “Common in the houses of the town of Maldonado, and its habits are similar to those of Mus Musculus.”—D.
6. Mus longicaudatus.
Plate XI.
Mus longicaudatus, Bennett, Proceedings of the Committee of Science and Correspondence of the Zoological Society of London for January, 1832, p. 2.
M. pallidè flavescenti-fuscus; corpore subtùs albo, levitèr flavo lavato; pedibus albis; tarsis permagnis; caudâ perlongâ; auribus parvulis.
Description.—Fur long and soft; general colour pale yellow-brown, the hairs of the ordinary fur being fulvous near the apex, and the longer hairs brown. On the sides of the body, cheeks, and external side of limbs, the fulvous hue prevails. The inner side of the limbs and the under parts of the body are white, but have an indistinct yellowish hue. All the hairs of the body are of a deep gray colour at the base. The ears are small, well clothed with hairs; those on the inner side are chiefly yellow; externally, on the fore part they are brown, and posteriorly whitish. The feet are of a flesh-colour, and furnished above with white hairs; the tarsi are but sparingly provided with minute hairs on the upper side, and are naked beneath: they are of unusually large size. The fore feet are of moderate[[18]] size, and furnished with a very large carpal tubercle. The tail is very nearly double the length of the body, if the latter be measured in a straight line; it is of a brownish flesh-colour above, paler beneath, and sparingly furnished with minute bristly hairs; those on the upper surface being brown, and on the under side white. The hairs of the moustaches are long, of a black colour, and grayish at the apex.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 3 | 9 |
| of tail | 5 | 3 | |
| from nose to ear | 0 | 10½ | |
| of tarsus (claws included) | 1 | 1 | |
| of ear | 0 | 4 |
Habitat, Chile.
The most conspicuous characters of the present species consist in the immense length of the tail, and the great size of the hinder feet.[[19]] It is about equal in size to Mus Musculus; its form, however, is somewhat stouter; in colour it is much paler and brighter. The head is larger in proportion; the ears are smaller, and more densely clothed with hair; the fore feet are rather larger, and the fleshy tubercle on the under side of the wrist is also larger. The thumb nail is flattened, and rounded at the tip, as in Mus Musculus, but is longer, and more distinct than in that animal.
The skull of M. longicaudatus, (Plate 34, Fig. 1,) is considerably larger than that of the common mouse, but in form scarcely differs from it; its upper surface is rather more convex, and the interparietal bone proportionately less. The length of the skull is 1 inch; breadth, 6½ lines; distance between the forepart of the incisor, and the first molar of the upper jaw, 3½ lines. The dentition is figured in Plate 34, Figs. 1. b and 1. c.
The above account is drawn up from the same specimen as that from which Mr. Bennett took his description, and which was brought from Chile by Mr. Cuming, who states that the animal in question lives in trees, and constructs its nest with grass.
In Mr. Darwin’s collection, I find an animal which agrees in all the more important characters with the one above described, but differs in being of a deeper colour, (approaching more nearly, in this respect, to the common mouse,) and in having the tail a trifle shorter. The skull is about ¾ of a line shorter, but its proportions agree precisely: the proportions of the feet, and the general form of the animal, also agree. This specimen is likewise from Chile, (Lat 37° 40′,) and, according to Mr. Darwin, “overran the wooded country south of Concepcion, in swarms of infinite numbers. Captain FitzRoy, on his return from visiting the wreck of H. M. S. Challenger, had the kindness to bring me this specimen. So destructive was this little animal, that it even gnawed through the paper of the cartridges belonging to the people who were wrecked.”—D.
Mus elegans.
Plate XII.
Mus elegans, Waterh., Proceedings of the Zoological Society of London for February 1837, p. 19.
Eligmodontia typus, F. Cuvier, Annales des Sciences Naturelles for March 1837. Tom. 7. p. 169. Pl. 5.
M. suprà flavus, vellere pilis fuscescentibus adsperso, his ad latera, et prope oculos rarioribus; pilis pone aurem utramque, labiis, corpore subtùs, pedibusque niveis; auribus magnis; caudâ capite corporeque paulo longiore; tarsis longis subtùs pilis obsitis.
Description.—Fur very long and soft; general colour of the upper parts of the body pale brownish yellow; the lower portion of the cheeks, and the under parts of the body pure white: the hairs of the ordinary fur of the back are gray at the base, pale ochre near the apex, and brown at the apex; the longer hairs are brownish. On the sides of the body where the longer hairs are less numerous, the pale ochre colour prevails; the hairs on this part as on the back are deep gray at the base, but at a short distance from the apex they are white; nearer the tip shaded into yellow, and at the tip brownish: the limbs externally are of a pale yellow colour. The hairs of the throat and chest are pure white to the root, those on the belly are obscurely tinted with gray at the root. The feet are of a pale flesh-colour, and furnished with white hairs; the fore feet are of moderate size; the thumb nail is small and rounded, and the carpal tubercle is covered with hairs; the tarsi are long, and the white hairs extend over the whole of the under parts; the under side of the toes, however, are but sparingly furnished. There appears to be but one large tubercle on the under side of the tarsus, and this, which is situated near the base of the toes, is thickly covered with silvery-white hairs. The tail is long, pale brown above, and pale flesh-colour beneath; above, it is furnished with minute brown hairs, and on the under side with white hairs. The ears are rather large, of a pale flesh-colour, tolerably well clothed with hairs, which are of a pale yellow colour on the inner side, and white on the outer side—excepting on the fore part, where they are brown. A small tuft of white hairs springs from the base of the ear posteriorly. The hairs of the moustaches are moderate; black at the base, and grayish at the apex.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 3 | 7 |
| of tail | 3 | 9 | |
| from nose to ear | 1 | 0 | |
| of tarsus | 0 | 10 | |
| of ear | 0 | 6 | |
Habitat, Bahia Blanca, (September.)
Upon comparing the skull (Pl. 34, fig. 2, a.) of M. elegans with that of M. Musculus, the most evident points of distinction consist in the greater proportionate length of the nasal and frontal bones, and the slenderness of the zygomatic arch in the former animal. Length of skull 11 lines, width 6 lines, distance between front molar and outer side of incisors of upper jaw 3⅜ lines, length of nasal bones 4⅜ lines.
The dentition is figured in Pl. 34, figs. 2. b, and 2. c.
“Whilst bivouacking one night on shore, amongst some sand hillocks, this mouse, with its tail singed, leapt out of a bush which was placed on the fire. Its hind legs appeared long in proportion to the front, and it did not appear to be very active in endeavouring to make its escape.”—D.
Mus elegans is about equal in size to M. Musculus; the head is larger in proportion than in the latter, the ears are slightly larger, the tail is longer, and so are the tarsi. The large ears, long tail, and comparatively large size of the feet, combined with the greater size of the animal itself, will render it easy to distinguish this species from M. gracilipes and M. bimaculatus. From the last mentioned animal it moreover differs in having the head larger in proportion, the fur longer, and the colouring of the upper parts of the body somewhat darker. The white fur is almost confined to the under parts of the body, and there is but a small tuft of white hairs behind the ears, whereas in M. bimaculatus, the white fur extends considerably on the sides of the body, the outer side of the limbs are white, and there is a large and conspicuous white spot behind each ear.
In M. elegans the whole sole of the tarsus and the carpal tubercles are covered with hair. In Mus bimaculatus the hinder half of the tarsus only is covered with hair, and in M. gracilipes both the hinder half is covered, and there are some scattered hairs extending almost to the two tubercles, which are situated at the base of the longer toes.
The genus Eligmodontia of M. F. Cuvier, founded upon a species of mouse from Buenos Ayres, possesses nearly the same characters as the subgenus Calomys, established by me in the Proceedings of the Zoological Society for February 1837, and which included the animal above described, and two other species (M. bimaculatus and M. gracilipes). M. Cuvier’s genus is distinguished by there being only one large tubercle on the under side of the tarsus, and in having the carpal pad covered with hair as well as the pad of the tarsus. In these characters our present animal agrees, as it does also in size and in the relative proportions of the tail and tarsus, circumstances which induce me to believe they are identical.
In M. bimaculatus and M. gracilipes there are six naked tubercles on the under side of the tarsus, and the carpal pad is also naked. In having, however, the tarsus hairy beneath,[[20]] in dentition and in colouring, they agree so closely with M. elegans that I think they cannot be separated generically.
Mus bimaculatus.
Plate XII.
Mus bimaculatus, Waterh., Proceedings of the Zoological Society of London for February 1837, p. 18.
M. vellere pallidè ochraceo, pilis nigricantibus adsperso, his ad latera rarioribus; rostri lateribus, notá magná pone aurem utramque, artubus, corporeque subtùs niveis; auribus mediocribus; caudâ, quoad longitudinem, corpus fere æquante; tarsis ad calcem pilis argenteo-candidis obsitis.
Description.—Upper parts of the body of a very pale ochre colour, the longer hairs, however, are black, and at the apex grayish, and where they are numerous, as on the back and upper surface of the head, they give greater depth to the colouring; the cheeks and sides of the body are of an almost uniform pale, but bright yellow; the sides of the muzzle, the lower half of the cheeks, the lower portion also of the sides of the body, and the whole of the under parts, are pure white—each hair being uniform in colour to the root, and not, as is usually the case, gray at the root. There is likewise a large patch of pure white hairs behind each ear. The feet and tail are of a pale flesh-colour, and furnished with white hairs, with the exception of those on the upper surface of the latter, which are pale brown. The ears are also pale flesh-colour, clothed internally with yellow hairs; externally on the fore part, the hairs are brownish, and on the hinder part, white—they are rather large, and so are the feet. The tail is about equal to the body in length. The hairs of the moustaches are numerous and slender, and most of them are black at the base, and gray at the apex. The hinder half of the tarsus beneath is covered with minute silvery-white hairs; beside the ordinary tubercles, the anterior portion of the sole of the foot and the base of the toes beneath, are crowded with small rounded warts, which are much more numerous and conspicuous than in the common mouse.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 3 | 1 |
| of tail | 1 | 11 | |
| from nose to eye | 0 | 4½ | |
| from nose to base of ear | 0 | 8¾ | |
| of tarsus (claws included) | 0 | 8 | |
| of ear | 0 | 4½ |
Habitat, Maldonado, La Plata, (June.)
The skull of this animal, is rather shorter and broader than that of Mus Musculus, the upper surface is more arched, the zygomatic arch is much more slender, and the nasal bones are rather broader. In the convexity of the upper surface, and the slenderness of the zygomatic arch, this skull very nearly resembles that of M. gracilipes; this latter, however, has the zygomatic arch more convex, projecting more suddenly on the anterior part, and the interparietal bone smaller. Length of skull 10 lines, width 5½, length of nasal bones 4 lines, distance between the outer side of the incisors, of the upper jaw, and the first molar 2⅞ lines. See Plate 34, fig. 3. a.
The dentition is figured in Plate 34, figs. 3. b and c.
This mouse is rather less than M. Musculus, the tail is much shorter in proportion, the fur is longer and softer, and the ears are more distinctly clothed with hair.
The pale and delicate yellow colour of the upper parts of the body, and the pure white of the under parts, renders the present species conspicuous amongst its congeners. I may further remark that the white colour which in the Muridæ (when it occurs) is usually confined to the under part of the body, or extends but slightly on the sides, is in the present animal extended considerably on the sides of the body, and occupies an equal portion with the yellow of the upper parts. The name bimaculatus is applied to this animal on account of the two conspicuous white patches, which are situated behind the ears.
In affinity as well as in appearance it most nearly approaches to Mus gracilipes and M. elegans; with no other species of the genus Mus, here described, can it be confounded, since these only have the tarsus hairy beneath.
The principal points of distinction between the present animal and Mus elegans, are noticed in the account of that species.
“This mouse, when alive, had a very elegant appearance. A countryman, who brought it me, found six of them living together in one burrow.”—D.
Mus gracilipes.
Plate XI.
Mus gracilipes, Waterh., Proceedings of the Zoological Society of London, for February 1837, p. 19.
M. suprà flavo-lavatus; pilis pone aurem utramque, labiis, corporeque subtùs, albis; pedibus parvulis, gracilibus, carneis, suprà et ad calcem pilis albis tectis; caudâ gracili, pilis albis instructâ, quoad longitudinem corpus ferè æquante; auribus mediocribus; vellere mediocri et molli, pilis omnibus ad basin plumbeis.
Description.—General colour very pale yellowish brown, a tint produced by the admixture of black and pale fawn colour; the hairs of the ordinary fur being of the latter tint near the apex, and dusky at the apex, whilst the longer hairs are black. The feet, tail, under parts of the body and the sides of the muzzle, are pure white. All the hairs of the body, (which are soft, and of moderate length), are deep gray at the base. The ears are of moderate size, well clothed with hairs, of which those on the inner side are yellowish, and those on the outer, are brown on the anterior part, and white on the posterior. A small tuft of white hairs springs from the neck immediately behind the ears; this tuft is hidden when the ears are folded back. The tail is slender and short, (being not quite equal to the body in length) of a pale flesh-colour, and sparingly furnished with minute white hairs. The feet are very small and slender, and the naked parts are of a pale flesh-colour. The sole of the foot is covered with hairs; the toes beneath, and the tubercles (which are as in Mus Musculus), however, are naked. The hairs of the moustaches are of moderate length, and of a blackish colour, some of them, however, are grayish white.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 2 | 10 |
| of tail | 1 | 7 | |
| from nose to eye | 0 | 4⅓ | |
| from nose to ear | 0 | 8¼ | |
| of tarsus (claws included) | 0 | 6½ | |
| of ear | 0 | 4¼ |
Habitat, Bahia Blanca, (September.)
This species slightly exceeds the harvest mouse (Mus messorius) in size, its ears are considerably larger in proportion, and the tail is shorter. Compared with the common mouse (Mus Musculus) it is smaller, the tail is more slender, and shorter, and the feet are likewise more slender and proportionately much smaller; the ears are more distinctly clothed with hairs.
The principal points of distinction between this and the two preceding species are pointed out in the account of M. elegans.
Upon comparing the skull of M. gracilipes (Pl. 34, fig. 4. a.) with that of Mus Musculus, the most striking differences consist in its shorter and broader form, the upper surface being more arched, the interparietal bone has a relatively smaller antero-posterior diameter, the occipital region is more convex, and continued more gently and gradually into the upper region of the skull. The zygomatic arch, which is unusually slender, is more dilated (especially on the anterior part) thus giving a squareness to the general form. The nasal bones are not so much attenuated posteriorly. The length of the skull is 8⅞ lines, the greatest width is 5⅛ lines, and the distance between the outer side of the incisors and the front molar is 2¾ lines.
The dentition is figured in Plate 34, figs. 4. b and 4. c.
“This specimen was given me by Mr. Bynoe, the surgeon of the Beagle, who caught it amongst some long dry grass.”—D.
Mus flavescens.
Plate XIII.
Mus flavescens, Waterh., Proceedings of the Zoological Society of London, for February 1837, p. 19.
M. suprà colore cinnamomeo, lateribus capitis, corporisque, æquè ac pectore, auratis; gulâ abdomineque flavescenti-albis: pedibus sordidè albis: auribus mediocribus rotundatis, pilis flavis obsitis: caudâ, corpore, capiteque longiore, suprà fuscâ, subtùs sordidè albá: tarsis longis.
Description.—Fur long and moderately soft; general colour of the upper parts bright brownish yellow; on the sides of the head and body bright yellow; towards the rump of a deeper hue, and inclining to orange; under parts pale yellow, or yellow-white; chest yellow. The fur both of the upper and under parts of the body deep plumbeous at the base. Feet flesh-colour, covered above with white hairs: tarsi long, naked beneath. Ears small, tolerably well clothed with hairs; those on the inner side yellow, but many of them blackish at the base; on the outer side, the hairs are blackish on the fore part and yellow on the hinder part. The hairs of the ordinary fur of the back are of a deep rich yellow colour at the tip, and the longer hairs are blackish. The tail is long, deep brown above and whitish beneath, the hairs of the moustaches are rather short and slender, and of a brownish colour. Thumb nail small and rounded.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 3 | 9 |
| of tail | 4 | 1½ | |
| from nose to ear | 1 | 0 | |
| of tarsus | 1 | 0½ | |
| of ear | 0 | 4½ |
Habitat, Maldonado, La Plata, (June.)
This species is slightly larger than the common mouse; the head is rather larger in proportion; the ears are rather smaller and more distinctly clothed with hair; the tail and tarsi are much longer in proportion. Its bright yellow colouring and proportions distinguish it from any of the species described in this work. Of this animal I do not possess the skull, nor of the teeth do I possess more than the first and second molars of the upper jaw, and the second and last of the lower jaw. These are figured in Plate 34, figs. 5. a, and 5. b.
Mus Magellanicus.
Plate XIV.
Mus Magellanicus, Bennett, Proceedings of the Zoological Society of London for December 1835, p. 191.
M. suprà fuscus, subtùs cinerescenti-albus, pallidè flavo lavatus; auribus mediocribus pilis fuscis obsitis; caudâ corpus caputque æquante; tarsis longis, pilis sordidè albis obsitis.
Description.—Fur very long and moderately soft, general colour deep brown; the hairs of the ordinary fur are gray, tipped with yellowish brown; the longer hairs are black; the sides of the body are yellowish; the under parts are gray-white with a faint yellowish tint, each hair being gray tipped with yellowish white. The ears are rather small, well clothed with hairs; those on the inner side are blackish tipped with yellow, and on the outer side they are blackish on the fore part and dusky on the hinder part. The fore feet are of moderate size, the thumb nail is short and rounded; the tarsi are rather long; both fore and hinder feet are of a brownish colour, and covered above with dirty gray hairs. The tail rather exceeds the head and body in length; it is brown above and dirty white beneath. The hairs of the moustaches are numerous and long, of a brownish colour at the apex and black at the base.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 4 | 3 |
| of tail | 4 | 2 | |
| from nose to ear | 1 | 0½ | |
| of tarsus | 1 | 1 | |
| of ear | 0 | 5 | |
Habitat, Port Famine, Strait of Magellan.
This mouse is larger than Mus Musculus; the tail is rather longer in proportion; the tarsi much longer; the ears are not quite so large in proportion to the head, (which greatly exceeds that of Mus Musculus in size,) and they are densely clothed with hair. The fur is longer. In colour, the animal here described is rather darker than the common mouse. I have one specimen however before me which very nearly agrees in this respect.
The dentition is figured in Plate 34, figs. 6, a. and 6, b.
From the attention which Mr. Darwin bestowed upon the Muridæ of the southern parts of South America, I presume his collection affords materials for a tolerably complete monograph of the species of that portion of the globe. The species above described, however, does not occur in Mr. Darwin s collection, but is here introduced in order to make the work more complete, and that I might more clearly point out the distinctions which exist between it and other species here described, the account given by Mr. Bennett in the Proceedings being very short.
Mus arenicola.
Plate XIII.
Mus arenicola, Waterh., Proceedings of the Zoological Society of London, for February 1837, p. 18.
M. suprà fuscus, subtùs cinerescenti-albus, pallidè flavo tinctus; auribus mediocribus rotundatis, pilis flavis fuscisque obsitis; caudâ quoad longitudinem corpus æquante; pedibus cinerescenti-albis: tarsis mediocribus.
Description.—Fur long, moderately soft; general colour deep brown; sides of the body with a very obscure yellowish hue; under parts dirty gray with a faint yellow tint. All the fur deep gray at the base; the hairs of the upper part of the body obscurely annulated with yellowish brown near the apex, and dusky at the apex; the longer hairs are black. Feet brownish, covered above with brown-white hairs; tarsi short. Tail short, blackish above, brown-white beneath. Ears small, well clothed with hairs; those on the inner side are yellow at the apex and gray at the base; on the outer side they are of a brownish colour, and on the fore part blackish. The hairs of the moustaches are short and slender, and of a brownish colour. The head is large.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 4 | 3 |
| of tail | 2 | 9 | |
| from nose to ear | 1 | 0 | |
| of tarsus (claws included) | 0 | 10 | |
| of ear | 0 | 4½ |
Habitat, Maldonado, La Plata, (June.)
This species is rather larger than the common mouse; its head is proportionately larger, the ears are smaller, the tail considerably shorter, and the fur longer, and in colouring it is a little darker. In size and colour it resembles M. Magellanicus, but the shorter tail and tarsi, and the smaller size of the ears will serve to distinguish it.
The skull of Mus arenicola, Plate 34. fig. 7, a, is rather larger than that of Mus Musculus, the nasal portion is broader, the interparietal bone is much smaller, especially in antero-posterior extent; the zygomatic arches are more slender, and the incisive foramina are broader. The horizontal ramus of the lower jaw (Pl. 34. fig. 7, d.) is rather less curved, the coronoid process is more elongated, and the condyloid is narrower and also larger. The length of the skull is 11 lines and a half; the width is 6½ lines. The molars of the upper jaw are figured in plate 34 fig. 7, b. and those of the under jaw, fig. 7, c.
“This specimen was caught on the open grassy plain, by a trap baited with a piece of bird; it is, however, very abundant in the sand hillocks near the coast of the Plata.”—D.
13. Mus brachiotis.
Plate XIV.
Mus brachiotis, Waterh., Proceedings of the Zoological Society of London for February 1837, p. 17.
M. suprà obscurè fuscus, subtùs obscurè griseo tinctus; pedibus griseo-fuscis; auribus parvulis; caudâ quoad longitudinem, corpus ferè æquante: vellere longo et molli.
Description.—Fur soft, very long, and dense; ears very small; general colour brown: the hairs of the upper parts, and sides of the head and body are of a deep gray at the base, black at the apex, and narrowly annulated with deep yellow near the apex; on the throat and belly they are of a paler gray at the base, and grayish white at the apex. The ears are well clothed with brown hairs both within and without, and are for the most part hidden by the long fur of the head. The hairs covering the upper side of the feet are of a palish ashy-brown colour, and the fleshy portion appears to have been brown. The tail is well clothed with hairs, so that the scales are scarcely visible; on the upper side of the tail the hairs are brownish black, and on the under side, they are dirty white. The incisors are very slender; those of the upper jaw are of a very pale yellow colour, and those of the lower are white, or nearly so. The muzzle is slender, and pointed.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 4 | 9 |
| of tail | 2 | 8 | |
| from nose to base of ears | 1 | 2 | |
| of tarsus (claws included) | 0 | 11 | |
| of ear | 0 | 3 |
Habitat, Chonos Archipelago, (December.)
This mouse is considerably larger than Mus Musculus, and the great length and density of its fur, causes it to appear much stouter in its proportions; its colouring is darker, the tips of the hairs being much more narrowly annulated with yellow than in that species. The very small size of the ears will serve to distinguish the present animal from its congeners—Mus longipilis, M. Renggeri, M. arenicola, &c.
The molar teeth of the upper jaw are figured in Plate 34. fig. 8, a; and fig. 8, b, represents the middle and last molars of the lower jaw.
“Inhabited a very small island, covered with thick forest, in the central part of the Chonos Archipelago.”—D.
A mouse obtained on the islets adjoining the east coast of Chiloe (where Mr. Darwin says it was common) differs from the above in being a little smaller, the tail is rather longer, and the ears are a trifle larger. In the feet, claws, colouring and character of the fur it agrees, and likewise in the pale colour and slenderness of the incisors. Its dimensions are as follows:—
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 4 | 0 |
| of tail | 3 | 0 | |
| of tarsus (claws included) | 0 | 10 | |
| from nose to ear | 0 | 10½ | |
| of ear | 0 | 4 |
I have not the means of satisfying myself whether this be a distinct species or not; but I think it is not.
“The nature of the country where this specimen was procured is nearly the same as in that part of the Chonos Archipelago, 150 miles to the south, where the first was obtained.” D.
14. Mus Renggeri.
Plate XV.—Fig. 1.
Mus olivaceus, Waterh., Proceedings of the Zoological Society of London, for February 1838, p. 16.
M. corpore suprà subolivaceo, subtùs cinerescente; auribus mediocribus, rotundatis, pills parvulis fuscescentibus obsitis; caudâ corpore breviore, pilosâ, suprà fuscâ subtùs albescente; pedibus pilis fuscescentibus tectis.
Description.—Fur moderate; ears moderate; tail shorter than the body; general colour gray washed with yellow; under parts grayish white. On the upper parts and sides of the head and body the hairs are gray, broadly annulated with yellow near the apex, and dusky at the apex; the mixture producing a yellowish gray tint, approaching somewhat towards olive:—the hairs on the under parts of the body and throat are deep gray at the base, and white at the apex; the hairs of the feet are brownish-white. The tail is tolerably well clothed with hairs; those on the upper surface are brown, and those on the under are dirty white. The ears are well clothed, both externally and internally, with hairs of the same colour as those on the upper parts of the body. The hairs of the moustaches are for the most part whitish, and black at the base. The upper incisors are pale yellow, and the lower incisors are yellowish white.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to the root of tail | 5 | 1 |
| of tail | 2 | 8 | |
| from nose to base of ears | 1 | 2 | |
| of tarsus (claws included) | 0 | 11 | |
| of ear. | 0 | 5 |
Habitat, Valparaiso (August and September,) Coquimbo (May.)
Subsequent to the description of this species, under the name of M. olivaceus in the Zoological Society’s Proceedings, I have imagined that perhaps that name might mislead as regards the colouring of the animal;—it certainly has a slight olive hue, but it is not very evident. I have therefore changed the name, and substituted that of the author of the “Naturgeschichte der Säugethiere von Paraguay,” &c.
In the collection there are three specimens of the present species; in one of these the hairs of the upper part and sides of the body are annulated with yellowish white, instead of yellow; hence the general hue of these parts is nearly gray.
Mus Renggeri is larger than Mus Musculus, and much stouter in its proportions; the fur is shorter, much less dense, and less soft than in Mus brachiotis.
“It inhabits dry stony places, where only a few thickets grow.”—D.
15. Mus obscurus.
Plate XV.—Fig. 2.
Mus obscurus, Waterh., Proceedings of the Zoological Society of London for February 1837, p. 16.
M. suprà fusco-nigrescens, subtùs flavescens; pedibus obscurè fuscis; unguibus longiusculis; auribus mediocribus; caudâ corpore breviore, suprà nigrescente, subtùs sordidè albâ; vellere mediocri, molli.
Description.—Head large; ears moderate; tail shorter than the body; fur rather long and glossy; the general hue of that of the upper parts and sides of the head and body is blackish brown, and that of the under parts is dirty yellowish white. The hairs on the upper parts are of a deep lead colour at the base, black at the apex, and narrowly annulated with dark yellow near the apex; those of the throat and belly are lead colour at the base and yellowish at the tip; the chin is white: around the eye, and on the lower part of the cheeks a deep yellow tint prevails. The ears are well clothed with hairs both externally and internally, and these are for the most part of a deep brown colour, as are also the hairs which cover the feet. The tail is well clothed with hairs, those on the upper surface are black, and those on the under are dirty white. Both upper and lower incisors are yellow, but the lower are paler than the upper.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 5 | 3 |
| of tail | 2 | 7 | |
| from nose to ears | 1 | 2½ | |
| of tarsus (claws included) | 0 | 11½ | |
| of ear | 0 | 4 |
Habitat, Maldonado, La Plata, (June.)
The present species, like the foregoing, is much stouter than the common mouse (Mus Musculus), its colour is much darker. In possessing a glossy fur it differs from most of its congeners; its head is also proportionately larger, and the incisors are much stronger.
The molars of the upper jaw are figured in plate 34, fig. 9, a,—and fig. 9, b, represents those of the under jaw.
“Very abundant in gardens and hedges, far from houses; and was easily caught in traps baited either with cheese or meat.”—D.
16. Mus xanthorhinus.
Plate XVII.—Fig. 1.
Mus xanthorhinus, Waterh., Proceedings of the Zoological Society of London, for January 1837, p. 17.
M. suprà fuscus flavo lavatus; subtùs albus; rhinario flavo; auribus parvulis, intùs pilis flavis obsitis; mystacibus longis, canis, ad basin nigrescentibus: caudâ corpore breviore, suprà fuscâ, ad latera flavescente, subtùs sordidè albâ: pedibus anticis, tarsisque flavis, digitis albis: vellere longo, molli.
Description.—Fur moderately long and loose; ears rather small; tail shorter than the body; general colour gray washed with yellow, the yellow colour prevailing, especially on the sides of the body; muzzle, inner side of ears, and tarsus, of a rich yellow colour; toes, chin, throat, under parts of body, and rump, white; all the fur deep gray at the base; the hairs on the upper parts and sides of the body broadly annulated near the apex with rich yellow, and at the apex dusky; on the under parts of the body the hairs are broadly tipped with white. Tail rather sparingly furnished with hair, that on the upper surface brown, on the sides yellow, and on the under surface whitish. The hairs of the moustaches are white—some of them dusky at the base. The incisor teeth are rather slender, and of a pale yellow colour.
| In. | Lines. | ||
|---|---|---|---|
| Length | from nose to root of tail | 3 | 6 |
| of tail | 1 | 7½ | |
| from nose to ear | 0 | 10 | |
| of tarsus (claws included) | 0 | 9 | |
| of ear | 0 | 3¾ |
Habitat, Hardy Peninsula, Tierra del Fuego, (February.)
The white, which is usually confined to the under parts of the body, in this species extends slightly on the sides of the body, and the lower portion of the cheeks.
“This species was caught on the mountains, thickly covered with peat, of Hardy Peninsula, which forms the extreme southern point of Tierra del Fuego.”—D.