INDEX

[1]. Zool. Anzeiger, xvi, 1893, pp. 271–5.

[2]. On the morphology of the Myriopoda, Proc. Amer. Phil. Soc. 1883, pp. 197–209.

[3]. Morphology and classification of the Pauropoda; also American Naturalist, 1897, p. 410.

[4]. The term which we proposed for this hypothetical ancestor of insects, “Leptus-like” or “Leptiform,” was an unfortunate one, since the name Leptus was originally given to the six-legged larva of a mite (Trombidium), the origin of the mites and other Arachnida being entirely different from that of the myriopods and insects.

[5]. Proc. Bost. Soc. Nat. Hist., xvi, 1873, p. 3.

[6]. American Naturalist, May, 1880, pp. 375, 376.

[7]. Zoologische Anzeiger, Bd. xx, 1897, pp. 125 and 129. He also states that Campodea resembles the myriopods, especially Geophilus, in the primitive band at first lying on the surface of the yolk, and in the absence of an amniotic cavity; also before hatching the abdomen is pressed against the thorax, as in myriopods.

[8]. “Scolopendrella has very remarkable antennæ; they may be compared each to a series of glass cups strung upon a delicate hyaline and extensible rod of uniform thickness throughout; so that, like the body of the creature, they shrink enormously when the animal is irritated or thrown into alcohol, and they then possess scarcely two-thirds the length they have in the fully extended condition, their cup-like joints being drawn close together, one within the other. Peripatus, Japyx, many (if not all) Homoptera, and the S. Asiatic relatives of our common Glomeris have all more or less extensible antennæ.” (Wood-Mason, Trans. Ent. Soc., London, 1879, p. 155.)

[9]. Lassaigne gave it the name of entomoline.

[10]. Miall and Denny ex Krukenberg; Kolbe gives the formula as C9H15NO6 or C18H15NO12. As the result of his recent researches, Krawkow (Zeits. Biol., xxix, 1892, p. 177) states that the chemical composition of chitin may prove to be somewhat variable.

[11]. On allowing portions of a locust, a piece of the integument of Limulus, a scorpion, and a myriopod to soak for a month in white potash, neither were dissolved or affected by the reagent.

[12]. We may add, while correcting the proofs of this book, that the important summary, by Uzel, of his work on the embryology of Campodea appears in the Zoologischer Anzeiger for July 5, 1897. He observes that the premandibular segment in the embryo is very distinct, and that the two projections arising from it persist in the adult. “Campodea is now the first example where these appendages are present in the sexually mature insect and function as constituents of the completed mouth parts. I propose for these hitherto overlooked structures the name of intercalary lobes.” They each form a slightly developed chitinous lobe covering a gap between the base of the labium and the fused external lobe and palpus of the first maxillæ (which are inclined near the labium) in place of the mandibles which have sunken inward. Uzel also homologizes these appendages with two similar projections (Höcker) observed in the embryo of Geophilus by Zograf to be situated in front of the mandibles. Heymons has also detected this segment in the embryo of Lepisma.

[13]. While these pages are still in type, we may add, in confirmation of this view, that Uzel states, from his researches on the embryology of Campodea, that the maxillary tergites of the embryo only slightly share in building up the tergal region (occiput) of the head, but that they form the genæ of the maxillary segments. (Zool. Anzeiger, July 5, 1897, p. 235.)

[14]. Miall and Denny in their work on the cockroach, in describing the labium, remark: “The upper edge is applied to the occipital frame, but is neither continuous with that structure nor articulated thereto. By stripping off the labium upwards it may be seen that it is really continuous with the chitinous integument of the neck” (p. 95). This is, we think, a mistaken view, as proved by the embryology of the Odonata and of Nematus. Our statements on this subject were first published in part in 1871, and more fully in the third Report, U. S. Ent. Commission, 1883, pp. 284, 285. We also stated that all the gular region of the head probably represents the base of the primitive second maxillæ.

[15]. After we had arrived at this conclusion, and written the above lines, we received the Zoologischer Anzeiger for March 29, 1897, in which Dr. N. Léon publishes the same view, stating that each side of the submentum is the homologue of the cardo, and each side of the mentum corresponds to the stipes of a single maxilla (p. 74).

[16]. Miall and Denny were the first to homologize the paraglossæ with the galea and lacinia, showing the complete resemblance of the second maxillæ to the first pair, remarking that “the homology of the labium with the first pair of maxillæ is in no other insects so distinct as in the Orthoptera.” We have also independently arrived at a similar conclusion, but believe that the mentum corresponds to the first maxillary cardo, and the palpifer to the first maxillary stipes, the sclerite of each maxilla being fused to form the base of the labium, i.e. the unpaired mentum and submentum.

[17]. Uzel states that what is regarded as the ligula of Campodea is formed from the sternite of the first maxillary segment; while the two parts regarded as paraglossæ grow out from the sternite of the mandibular segment, and these three structures together he regards as the hypopharynx. (Zool. Anzeiger, July 5, 1897, p. 234.)

[18]. See, also, Breithaupt, Ueber die Anatomie und die Functionen der Bienenzunge, 1886. It confirms and extends Cheshire’s work.

[19]. Cholodkowsky, Zool. Anz., ix, p. 615; x, p. 102.

[20]. Zool. Anz., ix, p. 711.

[21]. Ent. Amer., v, p. 110, Pl. II, Fig. 7.

[22]. In his account of his studies on the locomotion of insects, De Moor states that he obtained the track of each of the feet in different colors by coating them with different pigments; the insect, as it moved, left its track on a strip of paper. (Archives de Biologie, Liège, 1890.)

[23]. Carlet and also De Moor (1890) confirm Graber’s statement that in beetles the first and last appendages on the same side are in contact with the ground, while the middle one is raised. On the other side of the body the middle appendage is on the ground and the first and last one raised.

[24]. Trans. Amer. Ent. Soc. xx, p. 168.

[25]. Proc. Ent. Soc. London. Feb. 19, 1896. Heymons also shows that the germs of the elytra of the larva of Tenebrio molitor in the prepupal stage are like those of other insects. (Sitzungs-Ber. Gesell. natur f. Freunde zu Berlin, 1896, pp. 142–144.)

[26]. Zur Entwickelungsgeschichte und Reproductionsfähigkeit der Orthopteren. Von Vitus Graber. Sitzungsberichte d. math.-naturw. Classe der Akad. d. Wissensch., Wien. Bd. lv, Abth. i, 1867; also Die Insekten.

[27]. On the transformations of the common house fly, by A. S. Packard, Jr. Proceedings Boston Society of Natural History, vol. xvi, 1874. See Pl. 3, Figs. 12a, 12b.

[28]. See our Guide to the Study of Insects, p. 66, Figs. 65, 66.

[29]. Our Common Insects, 1873, p. 171.

[30]. Compare the observations of Palmén, Gerstäcker, Vayssière, and others.

[31]. Beiträge zur Kenntniss der Termiten. Jenaische Zeitschrift für Naturwissenchaft, Bd. ix, Heft 2, p. 253, 1875. Compare, however, Palmén’s Zur Morphologie des Tracheensystems, Helsingfors, 1877, wherein he opposes Müller’s view and adopts Gegenbaur’s. See p. 8, footnote.

[32]. Pancritius, who also adopted Müller’s views, lays much stress on the fact that in larvæ of some orders the tracheæ do not enter the rudimentary wings until the end of larval life, and hence the wings have not originated from tracheal gills, but were originally “perhaps only protective covers for the body.”

[33]. Reproduced from the author’s remarks in Third Report U. S. Ent. Commission, pp. 268–271, 1883.

[34]. Von Lendenfeld, however, points out the fact that Straus-Durckheim proved that the wings of beetles are moved by a complicated system of numerous muscles. “In the Lepidoptera I have never found less than six muscles to each wing, as also in the Hymenoptera and Diptera.” “The motions of the wings of Libellulidæ are the combined working of numerous muscles and cords, and of a great number of chitinous pieces connected by joints.”

[35]. Heymons, however, denies that the so-called cerci in Odonata are such, and claims that they are the homologues of the “caudal processes” (superior terminal appendages of Calvert), because they arise from the tenth abdominal segment.

[36]. Amer. Nat., iv, December, 1870.

[37]. Handbuch der Zoologie, p. 17, 1863, Fig. 162.

[38]. In my account of the anatomy of Melanoplus spretus, 1st Report U. S. Entomological Commission, p. 259, I have called these the infra-anal flaps or uro-patagia.

[39]. It has been suggested to us by A. A. Packard that the power possessed by insects of transporting loads much heavier than themselves is easily accounted for, when we consider that the muscles of the legs of an insect the size of a house-fly (¼ inch long), and supporting a load 399 times its own weight, would be subjected to the same stress (per square inch of cross-section) as they would be in a fly 100 inches long of precisely similar shape, that carried only its own weight; from the mechanical law that, while the weight of similar bodies varies as the cube of the corresponding dimensions, the area of cross-section of any part (such as a section of the muscles of the leg) varies only as the square of the corresponding dimensions. In short, the muscles of a fly carrying this great proportional weight undergo no greater tension than would be exerted by a colossal insect in walking.

[40]. This has been shown to be the case by Michels, who states that each commissure is formed of three parallel bundles of elementary nerve-fibres, which pass continuously from one end of the ventral or nervous cord to the other. “The commissures take their origin neither out of a central punctsubstanz (or marksubstanz), nor from the peripheral ganglion-cells of the several ganglia, but are mere continuations of the longitudinal fibres which decrease posteriorly in thickness, and extend anteriorly through the commissures, forming the œsophageal ring, to the brain.”

[41]. The following extract from Newton’s paper shows, however, that the infra or subœsophageal ganglion, according to Faivre, has the power of coördinating the movements of the body; still, it seems to us that the brain is primarily concerned in the exercise of this power, as the nerves from the subœsophageal ganglion supply only the mouth-parts. “The physiological experiments of Faivre in 1857 (Ann. des Sci. Nat. tom. viii, p. 245), upon the brain of Dyticus in relation to locomotion, are of very considerable interest, showing, as they appear to do, that the power of coördinating the movements of the body is lodged in the infraœsophageal ganglion. And such being the case, both the upper and lower pairs of ganglia ought to be regarded as forming parts of the insect’s brain.”—Quart. Jour. Micr. Sc., 1879, p. 342.

[42]. The arthropod protocerebrum probably represents the annelid brain (supraœsophageal ganglion). The antennal segment (deutocerebrum), with the premandibular (intercalary) segment (tritocerebrum) originally postoral, have, as Lankester suggests, in the Arthropoda moved forward to join the primitive brain. See Wheeler, Journ. Morphology, Boston, viii, p. 112.

[43]. Viallanes’ assertion that the instincts of the horse-flies and dragon-flies are “lower” than those of the locusts, may, it seems to us, well be questioned.

[44]. A. S. Packard, Experiments on the vitality of insects, Psyche, ii, 17, 1877.

[45]. Waterhouse, Trans. Ent. Soc., London, 1889, p. xxiv.

[46]. J. Müller, Physiology of the Senses. Trans. by Baly, copied from Lubbock, p. 176.

[47]. Hauser here uses the word taster, but this means palpus or feeler. It is probably a lapsus pennæ for teeth (Kegeln).

[48]. In 1870 I observed these sense-pits in the antennæ and also in the cercopoda of the cockroach (Periplaneta americana). I counted about 90 pits on each cercus. They are much larger and much more numerous than similar pits in the antennæ of the same insect. I compared them to similar pits in the antennæ of the carrion-beetles, and argued that they were organs rather of the smelling than hearing. (Amer. Nat., iv., Dec. 1870.) Organs of smell in the flies (Chrysopila) and in the palpi, both labial and maxillary, of Perla were described in the same journal (Fig. 270). Compare Vom Rath’s account of the organs in the cercopods of Acheta (Fig. 271); also the singular organ discovered by him on the end of the palpus of butterflies, in which a number of hair-like rods (sh) are seated on branches of a common nerve (n, Fig. 272).

[49]. Forel, however (Recueil Zoologique Suisse, 1887), denies that these tympanic organs are necessarily ears, and thinks that all insects are deaf, with no special organs of hearing, but that sounds are heard by their tactile organs, just as deaf-mutes perceive at a distance the rumbling of a carriage. But he appears to overlook the fact that many Crustacea, and all shrimps and crabs, as well as many molluscs, have organs of hearing. The German anatomist Will believes that insects hear only the stridulation of their own species. Lubbock thinks that bees and ants are not deaf, but hear sounds so shrill as to be beyond our hearing.

[50]. Weismann, Die nachembryonale Entwicklung der Musciden. Zeitschr. für wissen. Zoologie, xiv, p. 196, 1864.

[51]. Plateau (1877) states that the digestive fluid of insects, as well as of Arachnids, Crustaceans, and Myriopods, has no analogy with the gastric juice of vertebrates; it rather resembles the pancreatic sugar of the higher animals. The acidity quite often observed is only very accessory in character, and not the sign of a physiological property. “Farther, I have found it in insects; Hoppe-Seyler has demonstrated in the Crustacea, and I have proved in the spiders, that the ferment causing the digestion of albuminoids is evidently quite different from the gastric pepsine of vertebrates; the addition of very feeble quantities of chlorhydric acid, far from promoting its action, retards or completely arrests it.” (Bull. Acad. roy. Belgique, 1877, p. 27.)

[52]. The word grès we translate as the layer of gum. Not sure of the English equivalent for grès, I applied to Dr. L. O. Howard, U. S. Entomologist, who kindly answers as follows: “I have consulted Mr. Philip Walker, a silk expert, who writes me the following paragraph: ‘Grès, as I understand it, is the gum of the silk fibre, hence the French name for raw silk, grèye, which is in distinction to the silk that has been boiled out in soap after twisting, or throwing, as it is called. As I understand it, the silk fibre is composed of the grès and fibroin. The former is soluble in alkali, like soap water, and the latter is not.’” While Blanc considers the grès as the product of a special secretion of the wall of the reservoir, Gilson regards its production as simultaneous with that of the silk or of the fibroin (l.c. 1893, p. 74).

[53]. On cytological differences in homologous organs. Report 63d meeting of British Assoc. Adv. Sc. for 1893. 1894. p. 913.

[54]. See also Giard, Bull. Soc. Ent. France, p. viii, 1894.

[55]. “The contents of the Malpighian tubules may be examined by crushing the part in a drop of dilute acetic acid, or in dilute sulphuric acid (10 per cent). In the first case a cover-slip is placed on the fluid, and the crystals, which consist of oblique rhombohedrons or derived forms, are usually at once apparent. If sulphuric acid is used, the fluid must be allowed to evaporate. In this case they are much more elongated, and usually clustered. The murexide reaction does not give satisfactory indications with the tubules of the cockroach.” (Miall and Denny, The cockroach, p. 129, footnote.)

[56]. “There is a curious analogy between the excretory organs of these insects and the mesonephros of some vertebrates, where a second, third, etc., generation of tubules is added to the primitive metameric series. When the embryonic number of Malpighian vessels persists in insects, the demand for greater excreting surface is supplied by a lengthening of the individual vessels.”

[57]. For the mode of adhesion of Cynips eggs, see Adler in Deutsche Ent. Zeits. 1877, p. 320.

[58]. Mercaptan is a mercury, belonging to a class of compounds analogous to alcohol, having an offensive garlic odor. Methyl mercaptan is a highly offensive and volatile liquid.

[59]. Embryonic or temporary glands, the “pleuropodia” of Wheeler, viz. the modified first pair of abdominal legs, occur in Œcanthus, Gryllotalpa, Xiphidium, Stenobothrus, Mantis (occasionally a pair on the second abdominal segment, Graber); Blatta, Periplaneta, Cicada, Zaitha, Hydrophilus, Acilius, Melolontha, Meloë, Sialis, Neophylax. (See Wheeler, Appendages of the First Abdominal Segment, etc., 1890.)

[60]. These midges owe their phosphorescence to bacteria in their bodies during disease.

[61]. Untersuchungen zur Anatomie und Histologie der Tiere, 1884, p. 72.

[62]. Zelle und Gewebe, 1885, p. 43. (See also our p. 217.)

[63]. Studien über die Lampyriden, Zeits. für wiss. Zool., xxxvii, 1882. Both Wielowiejski and M. Wistinghausen have completely disproved the view of Schultze, that the tracheæ end in star-like cells, where respiration takes place, as the “star-like cells” are simply net-like expansions of the peritoneal membrane of the tracheæ.

[64]. The following summary compiled from Krancher, is translated, with some minor changes, from Kolbe’s work.

[65]. Miall and Denny state that in the cockroach the abdominal spiracles are permanently open, owing to the absence of a valve, but communication with the tracheal trunk may be cut off at pleasure by an internal occluding apparatus.

[66]. Zur Entwicklungsgeschichte der Biene, Zeitschr. wissens. Zoologie, xx, p. 519, 1870.

[67]. Die Entwicklung der Dipteren im Ei, Zeitschr. wissens. Zoologie, xiii, 1863.

[68]. Amer. Naturalist, May, 1886, p. 438.

[69]. Zeitschr. wissens. Zoologie, xl, 1884, Taf. xix, Fig. 8, T.

[70]. Science, 1893, pp. 44–46.

[71]. Art. Thorax, Todd’s Cycl. of Anat. and Phys.

[72]. The mesothoracic stigmata are open in Carabus, Potamophilus, Elmis, Macronychus, Buprestis, Elater, Lampyris, Lycus, Triphyllus, Eucinetus, Dascillus, Psephenus, Ergates, Micralymna, and probably many others. The metathoracic stigmata are open in Lycus and Elmis.

[73]. In the Hymenoptera the two pairs on the meso- and metathoracic segments are open in the Aculeata, also in the Siricidæ, among which sometimes that on the third segment is closed. In Pimpla and Microgaster (fully grown larvæ) only the mesothoracic stigmata are open.

Palmén adds that most dipterous larvæ are amphipneustic; Cecidomyia, the Mycetophilidæ, Bibionidæ, and Stratiomys are typically peripneustic. (p. 92.)

Moreover, a single insect, as Sialis, may be apneustic as a larva, peripneustic as a pupa, and holopneustic in the imago stage.

[74]. Mr. J. W. Folsom, who has made the accompanying sketch of the nymph of Euphæa splendens in the Cambridge Museum, finds only seven pairs of gills, there being no traces of them on segments 1, 9, and 10. A stout trachea, he writes us, enters the base of each gill, and subdivides into several long branches, which course along the periphery. Hagen in his original account said there were eight pairs on segments 1–8 respectively.

[75]. Harris, Correspondence, p. 226, Pl. III., Fig. 7.

[76]. Nusbaum’s view has been questioned by Heymons, who, from his studies on the embryology of the cockroach (Periplaneta and Phyllodromia), Forficula, and Gryllus, concludes that the ectodermal ends of the sexual outlets owe their origin to an unpaired median hypodermal invagination, and that it is quite doubtful whether the ectodermal portions of the sexual passages of insects were ever paired (p. 104). On the other hand he appears, even throwing out the case of Ephemera, to have overlooked Nassonow’s discovery of paired outlets in the young of Lepisma.

[77]. Acta Acad. German., xxxiii, 1867, No. 2, p. 81. Quoted by Dr. Sharp, Insecta, p. 142.

[78]. Journ. Morph., iii, Boston, pp. 299, 300.

[79]. Proc. Boston Soc. Nat. Hist., xi, pp. 88, 89.

[80]. In the following general account of the embryology of insects, I have closely followed the admirable arrangement and description of Korschelt and Heider, in their Lehrbuch der vergleichenden Entwicklungsgeschichte der wirbellosen Thiere, pp. 764–846, often translating their text literally, though not omitting to state the results of other writers.

[81]. Korschelt and Heider state that no cellular embryonal membranes are present in Synaptera, Uljanin finding none in the Podurids. In the embryo of Isotoma walkerii we, however, observed a membrane which we compared to the larval skin of many Crustacea, and both Sommer and Lemoine have detected in eggs of the same group a cuticular larval skin which is provided with spines for rupturing the chorion. The amnion is also wanting in Proctotrupids (Ayers), and is rudimental in Muscidæ (Kowalevsky, Graber), in viviparous Cecidomyidæ, according to Metschnikoff, who also states that in certain ants of Madeira the envelopes are represented only by a small mass of cells in the dorsal region.

[82]. In Diptera the stomodæum may be dorsal, Dr. Pratt tells us.

[83]. Will (Aphis) and also Cholodkowsky’s statement (Blatta), as well as Balfour and Schimkewitch’s statements that the brain is at first disconnected from the ventral cord, are apparently erroneous.

[84]. The description perhaps applies not only to the cockroaches, but, as seen from the similar but fragmentary notices of Heider and of Wheeler on the Coleoptera, may be common to insects in general.

[85]. Report on the Rocky Mountain locust, etc. Ninth Annual Report U. S. Geol. and Geogr. Survey of the Territories for 1875, pp. 633, 634.

[86]. Orthoptera Europæa, 1853, p. 37.

[87]. In his Für Darwin (1863), Fritz Müller gives his reasons for the opinion that the so-called “complete metamorphosis” of insects was not inherited from the primitive ancestor of all insects, but acquired at a later period.

[88]. For further details see the 1st Report of the U. S. Entomological Commission, 1878, pp. 279–281.

[89]. See Köppen ueber die Heuschrecken in Südrussland, 1862, pp. 22, 23.

[90]. In Samouelle’s The Entomologist’s Useful Compendium, 1819. See Westwood’s Class. Insects, i, p. 2; Leach’s Ametabolia comprised the Thysanura (Synaptera) and the lice.

[91]. From the Greek μανός, scanty; μεταβολή, change.

[92]. Greek, ἤρεμα, quiet; μεταβολή, change.

[93]. At the same date (March, 1869) we independently suggested that the insects had originated from some form like the hexapodous young of Pauropus and Podura. In November, 1870, we suggested that the Thysanura and the hexapodous Leptus may have descended from some Peripatus-like worm. Afterwards (1871) we proposed for the ancestral form the term leptiform, which was later abandoned for Brauer’s term Campodea-form.

[94]. Amer. Naturalist, i, p. 85, 1867.

[95]. First Rep. U. S. Ent. Commission, p. 281–283.

[96]. Trans. Ent. Soc. London, iii, p. xv. See also Ashton, R. J., Trans. Ent. Soc. London, iii, 1841–43, pp. 157–159.

[97]. Proc. Bost. Soc. Nat. Hist., x, 1866, p. 283.

[98]. See Max Braun’s article entitled Ueber die histologischen Vorgange bei der Hautung von Astacus fluviatilis, with a full bibliography, in Semper’s Arbeiten aus dem Zool. zoot. Institut in Würzburg, ii, pp. 121–166. Also Semper’s Animal Life, p. 20. Trouvelot also discovered the moulting fluid. (Amer. Nat., i, p. 37.)

[99]. American Naturalist, xvii, May, 1883, pp. 547, 548.

[100]. Le Pelletier. A. M. L., Bulletin de la Société Philomathique, Paris, April, 1813.

[101]. Heineken, Carl. Observations on the reproduction of the members in spiders and insects. (Zool. Journ., 1829, vi, pp. 422–432.)

[102]. Bees and Bee-keeping, pp. 21, 22.

[103]. Butterflies, their structure, changes, and life-histories. New York, 1881, pp. 37–42. Butterflies of the Eastern United States and Canada, 1888, 1889. Also, Frail children of the air, 1895, pp. 232, 233 a. Dr. Chapman, however, finds that this piece in micropupæ has no connection whatever with the head or eye, but belongs rather with the prothoracic segment. (Trans. Ent. Soc. London, 1893, p. 102.) We have been able to confirm his statements, but still this piece is peculiar to the pupal state.

[104]. Rep. Ent. U. S. Dept. Agr., 1879, pp. 228, 229, Pl. IV, Fig. 4.

[105]. Monograph of bombycine moths, Pt. I, 1897. Figs. 24, 28, 29, 33, 34, 40, 77.

[106]. Amer. Naturalist, xii, pp. 379–383.

[107]. Hybocampa milhauseni, Dr. Chapman tells me, has a pupal spine (imperfectly present in Cerura) with which it cuts out a lid of the cocoon.

[108]. Riley’s Report for 1892, p. 203.

[109]. Philosophy of the pupation of butterflies, and particularly of Nymphalidæ, by Charles V. Riley. (Proc. Amer. Assoc. Adv. Science, xxviii, Saratoga Meeting, August, 1880, pp. 455–463.)

[110]. The homology of the suranal plate of the larva with the cremaster of the pupa, established by Riley in 1880, is also affirmed by Jackson (1888) and by Poulton, and for some years we have been satisfied that this is the correct view; Professor Hatchett-Jackson discovered it, he states, in 1876.

[111]. In his remarkable studies on the morphology of the Lepidoptera, Professor W. Hatchett-Jackson states his belief that Riley’s homology of the sustentors with the soles or plantæ of the anal prolegs, and the sustentor ridges with their limbs, is wrong, and that the eminences on either side the anal furrow, or the “anal prominences,” as they are termed by Riley, represent the prolegs, and that the sustentor ridges and sustentors are probably peculiar developments of the body of the 10th somite, found only in some Lepidoptera. From our examination of pupa of different families of moths, we are satisfied that Jackson’s view is the correct one. We have not found the sustentors and their ridges in the pupæ of the more generalized moths, but the vestiges of the anal legs are almost invariably present, their absence in the pupa of Nola and Harrisina being noteworthy.

[112]. We copy from Kirby and Spence their abstract of Herold’s conclusions: “The successive skins of the caterpillar, the pupa-case, the future butterfly, and its parts or organs, except those of sex, which he discovered in the newly excluded larva, do not preëxist as germs, but are formed successively from the rete mucosum, which itself is formed anew upon every change of skin, from what he denominates the blood, or the chyle after it has passed through the pores of the intestinal canal into the general cavity of the body, where, being oxygenated by the air-vessels, it performs the nutritive functions of blood. He attributes these formations to a vis formatrix (bildende Kraft).

“The caul or epiploon (fett-masse), the corps graisseux of Réaumur, etc., which he supposes to be formed from the superfluous blood, he allows, with most physiologists, to be stored up in the larva, that in the pupa state it may serve for the development of the imago. But he differs from them in asserting that in this state it is destined to two distinct purposes: first, for the production of the muscles of the butterfly, which he affirms are generated from it in the shape of slender bundles of fibres; and, secondly, for the development and nutrition of the organs formed in the larva, to effect which, he says, it is dissolved again into the mass of blood, and being oxygenated by the air-vessels, becomes fit for nutrition, whence the epiploon appears to be a kind of concrete chyle.” (Entwickelungsgeschichte der Schmetterlinge, pp. 12–27.) It seems that Herold was right in deriving the pupa and imago from the hypodermis (his rete mucosum), but wrong in denying that the germs did not preëxist in the young caterpillar, and wrong in supposing that the latter originated from the blood, also in supposing that the muscles owe their origin to the fat-body. Swammerdam, and also Kirby and Spence, were correct in supposing that the imago arose from “germs” in the larva, though wrong in adopting the “emboîtement” theory.

[113]. In the regions where the imaginal buds are not present (dorsal aspect of the prothorax, and abdomen), the epithelium (hypodermis) may proliferate independently of these buds.

[114]. We shall translate portions and, when the text allows, make an abstract of parts of Gonin’s clear and excellent account, often using his own words.

[115]. C. Herbert Hurst, The Pupal Stages of Culex.

[116]. Lowne on the Blow-fly, new edit., pp. 2, 41, Fig. 7.

[117]. Miall, Natural History of Aquatic Insects, pp. 136–138. Also Trans. Linn. Soc. London, V, Sept., 1892.

[118]. This account is translated from Korschelt and Heider, with some omissions and slight changes.

[119]. Westwood in his excellent account of this group remarks: “Hence, as well as from the account given by Jurine, it is evident that the pupa of the Stylops is enclosed in a distinct skin, and is also in that state enveloped by the skin of the larva, contrary to the suggestion of Mr. Kelly.” (Class. Insects, II. 297.) This is all we know about the supernumerary larval stages.

[120]. Some facts towards a life history of Rhipiphorus paradoxus. Annals and Magazine of Natural History for October, 1870.

TRANSCRIBER’S NOTES