The West Coast Helicoid Land Shells.
BY J. G. COOPER, M.D.
In the article on p. 259, Vol. III, of these Proceedings for April 2d, 1866, I suggested a division of the Californian Banded Helices into five subgenera, founded on the shells alone. Since then, Mr. G. W. Tryon has published a synopsis of all of them except H. facta in his “Journal of Conchology,” Vol. II, Part 4, for October, 1866, arranging them in the “genera” Aglaia, Arianta and Polymita, but differing essentially from Albers and other authors in the species he assigns to these groups. The types of these subgenera, however, differ so much from our species that it is easy to separate the shells by good subgeneric characters; and as they inhabit respectively South America, Europe, and Cuba, it is very probable that the animals differ still more. Until these have been compared, we may well hesitate in referring ours to the same groups, and must for the present be guided by the shells alone.
In examining these, the most striking and almost universal character we find is the presence of a dark band, generally pale margined, on one or both sides, and situated at or close to the breathing aperture in the animal’s mantle, apparently having some physiological connection with this opening. It is too uniform and general to be merely an ornamental marking, such as we find in many species, especially the tropical, which usually show no uniformity in the arrangement of their bands.
The next most constant characters are those derived from the nature of the surface, whether hirsute, with revolving grooves, smooth or variously sculptured, with wrinkles, zigzag or oblique patterns.
Although colors alone are usually unreliable as subgeneric characters, I am inclined to consider them as such in the case of these and some allied species, from their apparent connection with important organs. In fact the band, so constant in this large series of species, takes precedence of considerable variety of form, for the variations in outline, umbilicus, and peristome, though great in the extremes, are so gradually shaded and blended together in the whole series that no well-defined generic divisions can be founded on them, though useful for the minor grouping. The umbilicus especially is variable even in specimens of the same species, those from southern and arid regions being often nearly imperforate, and more conical than others.
Several Mexican species belong to the same series, such as H. Remondii Tryon, H. Griseola Pfeiff, and H. Berlandieriana Moric., the two last extending to Texas. Others, as H. Humboldtiana Val., scarcely differ from the typical Pomatia in form. I would, however, exclude the true Hygromias associated with these by Tryon. I would also exclude the plain or variegated species of Lower California, which approach nearer to Polymita. It must be observed that many of our species approach in form to others of allied groups, so that if we overlook characters of color and surface, we will be inclined to place in the same groups, Nos. 40 and 52, 24 and 32, 29 and 47, etc. Even in color Nos. 32 to 35 show an approach to the group of Lower California, but seem more closely allied to our series, having merely a geographical affinity to the former. Size is of little value, even as a specific character among the land shells, nearly all the species furnishing specimens twice as large as others of the same kind. The proportions of height to breadth are more reliable, but not constant.
The subgenus or division characterized by the band is scarcely distinguishable as a whole from the typical Helix, (type pomatia) of Europe, though the extremes vary greatly, simulating the three or more foreign genera to which various authors have attached them.[32]
Our species are distinct enough among themselves when the true specific characters here given are noted, though occasionally hybrids undoubtedly occur. Dr. W. Newcomb has raised many specimens in his garden in Oakland, combining the characters of Nos. 24, 25, 29, 31, and 43, in such manner that it is often impossible to determine which they belong to. Yet their natural locations are usually so widely separated that only occasionally can hybrids occur in a state of nature, and where several do inhabit one locality, as 24, 27, 28, 46 do at Santa Cruz, though nearly allied, intermediate forms are not found. Some of the so-called species are, however, scarcely more than hybrids or varieties, but the names are retained as indicating their differences, though almost every species is divisible into varieties as well marked or better. Thus the specimen described on p. 260 of this volume (from Mount Diablo) seems to be a hybrid between mormonum and ramentosa, and we also find specimens connecting the latter with 25, 26, and perhaps others.
Occasional links also occur, connecting many others of the banded species together.
A similar intermixing of species, where nearly allied, occurs among our marine shells wherever two or more encroach on each other’s limits; but the comparative rarity of the intermediate forms seems to indicate hybridity rather than specific identity of their allies.
It is probable that groups X and XI and XIII and XIV should be united, as the distinctive characters between them are not of first importance, and species of each are very closely similar otherwise. Parallel columns may be formed, as indicated on p. 260, in which close resemblances in form, number of whorls, etc., between species of the different groups may be shown, and this may be extended so as to show analogous parallels with those of other sub-families, or even families, but these resemblances do not indicate affinity, though very likely to mislead. A geographical arrangement of some groups is also indicated, though imperfectly, as there are no impassable limits between them. For special localities of many species, see vol. III, pp. 62, 115, 180, 259, and II, 91, 103.[33]
The Darwinian theory of development might be very beautifully illustrated by these banded snails, if we could find evidence that their various forms had all originated from a common stock (which might be the ramentosa, as that species now occupies a nearly central locality). But though fossil forms have been found differing considerably from their present representatives, there are others apparently as old, which show no such differences, and none of them show a tendency towards any common original type. The one referred to by Professor Whitney on p. 278, as found with the human skull of supposed pliocene (?) age, does not differ perceptibly from specimens of mormonum, now living near the locality. It retains even its band of color, which is soon lost in specimens imbedded near the surface, and this (if not preserved by its deep burial or incrustation) is strong evidence against a great antiquity of the skull. All other fossil Helicoids are considered postpliocene, at least so far as known in this State, though extinct species occur in Europe as far back as the Eocene.
The bandless species of the west coast slope, from lat. 33° to 49°, are added to the synopsis, to show their relations and analogies with the banded. The arrangement followed is essentially that of Tryon, except the addition of some he has omitted, or not yet published. The generic divisions are also reduced to groups, as the true generic characters are not yet settled. The lip is entirely wanting in the first family, but in the bandless Helicidæ of this coast, it becomes of great importance for grouping of species, (49 to 55) of which we have very few, while east of the Rocky Mountains there are more than fifty. Group III is also largely developed on the Atlantic slopes. The tendency now is to divide too much, which is as unnatural as to unite all under genus Helix, as many still do. It is probable that the divisions here called subfamilies, answer more nearly to the true genera than any others, though they require modification, and the selection of names applicable to them as genera, is a difficult task. To undertake to distinguish genera by the lingual teeth, mucous pores, or any other single character of the soft parts, is less practicable than to do it by the shells alone, and little if any more reliable. There may, however, be foreign shells closely resembling ours in form, which must still be separated on account of the animal.
I have omitted most of the compound terms used by authors to describe the forms or shells, as they are not used with any uniform system, and do not well define the differences between the various species of the same group. The dimensions are more reliable for separating allied forms. “Striæ” is also an indefinite term, used by various authors for lines of growth, revolving grooves or stripes of color, and is therefore never used alone in this article.
It is remarkable that no reversed species or variety has yet been found west of the Rocky Mountains.
Order PULMONIFERA.
Mollusca with or without shells, breathing by lungs, inhabiting the land, fresh or salt waters.
Subord. Geophila.
Terrestrial Molluscs. Section with external rounded shells.
Note.—The * indicates the original measurement of authors, in hundredths of an inch.
A. Shell with edge of mouth sharp.
Fam. Helicellidæ. Shell corneous, thin, polished, translucent, sometimes with internal teeth.
Subfam. Vitrininæ. Shell very fragile, whorls 2 or 3, the last greatly expanded, not covering the animal.
I Genus Binneya Cp. Ear-shaped, nearly flat, one-third the length of animal, spire none, corneous.
1 notabilis Cp. Whorls 2, pale brown, first with 30 delicate revolving ribs, epidermis expanded; diam. *0.46, alt. 0.12 in.
II Genus Vitrina Drap. Depressed subglobose, last whorl very large, swollen, imperforate, shining.
2 Pfeifferi Newc. Wh. 3, greenish white, suture finely margined, columella arched, spire flattened, diam. *0.19, axis 0.09.
Subfam. Helicellinæ. Shell thin, translucent, whorls 4 to 6, mouth moderate, surface smooth, pitted below or perforated.
III Group. Hyalina Feruss. Depressed globose, moderately umbilicate, or pitted, vitreous, shining, whorls uniform.
3 Breweri Newc. Wh. 5, pale corneous, umbilicus large, suture slightly channeled, aperture lunar; diam. *0.20, axis 0.10.
IV Group. Macrocyclis Beck. Discoid, widely umbilicate, growth lines often coarse, last whorl usually deflexed.
4 Newberryana W. G. Binn. Wh. 6, reddish-brown, flattened, mouth not deflexed, fine revolving striæ; diam. 1.43, axis 0.50.
5 Vancouverensis Lea. Wh. 5, yellowish-green, shining, very slight revolving grooves; diam. 1.10 to *1.25, axis 0.40.
6 sportella Gould. Wh. 5, pale-greenish, growth lines coarse, crossed by revolving grooves; diam. *0.50 to 0.70, axis 0.20 to 0.25.
7 Voyana Newc. Wh. 5, pale corneous, mouth much sinuated above, body whorl crossed by a thick callus; diam. *0.50, axis 0.15 to 0.20.
Subfam. Gastrodontinæ. Generally depressed conic, and lamellarly toothed inside, growth lines distinct, small.
V Group. Conulus Fitz. minute, conoid, whorls 4 to 6, narrow, aperture basal, transverse, perforate or not, without teeth.
8 chersina Say. Wh. 5-6, amber-yellow, imperforate, base indurated, smooth, shining; diam. 0.10 to 0.12, axis, 0.08.
9 chersinella Dall. Wh. 4½ to 5, yellowish, narrowly perforate, mouth oblique, growth ribs distinct; diam. *0.14, axis 0.09.
Subfam. Patulinæ. Thickish, epidermis opaque, form discoidal to subglobose, umbilicate, often striped or hirsute.
VI Group. Pseudohyalina Morse. Minute, convex discoid, nearly smooth, umbilicate, unicolor, whorls 3 to 5.
10 milium Morse. Wh. 3, greenish white, plano-convex, translucent, minute revolving grooves; diam. 0.05, axis 0.02. Nevada Co. and Angel Island, Rowell, Monterey, Canfield, San Francisco and Santa Cruz, rare. No revolving grooves seen.
11 minuscula Binn. Wh. 4, whitish, nearly flat, mouth sub-oval, whorls narrow, smooth, a parietal callus; diam. 0.09, axis 0.01.
12 conspecta Bland. Wh. 4, dark corneous, obtuse convex, smooth, mouth sub-circular, oblique; diam. 0.08 to 0.10, axis 0.04 to 0.05.
VII Group. Patula Held. Size moderate, convex-discoid, concave below, umbilicus showing all the whorls, unicolor.
13 Hornii Gabb. Wh. 4½, opaque, brown, sparsely hirsute, spire flattened, umbilicus a little contracted; diam. *0.16, axis 0.09.
14 Whitneyi Newc. Wh. 4, smoky-brown, smooth, nearly flat, umbilicus plainly perspective; diam. *0.20, axis 0.10.
15 Cronkhitei Newc. Wh. 4, yellowish corneous, a little convex, growth-ribs distinct, not plainly perspective; diam. *0.20, axis 0.15.
16 striatella Anth. Wh. 3-4, pale corneous, depressed convex, umbilicus large, shallow, growth-ribs faint; diam. 0.20, axis 0.15. The west slope specimens may be all of last species.
17 Durantii Newc. Wh. 4, light corneous, flat above, nearly smooth, umbilicus perspective, opaque; diam. *0.20, axis 0.07.
VIII Group. Helicodiscus? Morse. Planorboid, whorls visible below, several sets of internal teeth. (“Polygyra” Tryon, part.)
18 polygyrella Bland. Wh. 7 to 8, yellowish horn color, 3 teeth opposite mouth, 3 nearer mouth, 1 parietal; diam. *0.44, axis 0.19.
IX Group. Anguispira Morse. Large, rather heavy, subturbinate, strongly ribbed, grooved or striped, umbilicate.
19 Idahoensis Newc. Wh. 5, ashy corneous, very convex, 20 to 25 strong ribs on last whorl, fewer above; diam. *0.52, axis 0.45.
20 Cooperii W. G. Binn. Wh. 5 to 6, white, 1 or 2 brown distant bands or mottlings, fine revolving grooves; diam. 0.58 to 0.98, axis 0.35 to 0.37.
[34] 21 solitaria Say. Wh. 6, white to dark brown, 1 to 4 brown bands, or a var. (?) brown, with 1 pale band; diam. 1.00, axis 0.80.
22 strigosa Gould. Wh. 5, ashy to brown, usually 5 to 8 banded below middle, angled or carinate, revolving grooves; diam. 0.75 to 1.00, axis 0.28 to 0.50.
N.B. Nos. 13, 16, 18, and Group IX are found only east of California.
B. Shell with a distinct thickened lip.
Fam. Helicidæ. Epidermis thickish, opaque, colored, lip thickened, expanded, reflected or toothed. Large or moderate.
Genus Helix Linn. Form globose—conic to depressed carinate; umbilicus wide to very small or covered; lip thickened, sometimes a little expanded, and rarely tuberculate below, or continuous across body whorl. Color, (in our species) yellowish brown to black, with a darker band around the periphery and sutural region, generally margined on each side (at least when young) by a pale one.
†Band triple in young and thin specimens, (wanting in varieties. Bandless specimens of Nos. 24, 25, 27, 28, 33, have been noticed.) Colors, uniform brown or olivaceous, sometimes mottled. Obliquely reticulate grooved, or wrinkled-malleated. From forests of oak, etc., in middle regions, or moderate elevations southward.
X Group. (“Arianta” Albers, No. 23. “Polymita” Tryon, No. 24.) Form resembling H. pomatia, sculpture in zigzag or divaricate grooves. Subimperforate.
23 Californiensis Lea. Wh. 5, yellowish-olive, thin, band pale-margined, sculpture faint, subglobose; diam. 0.75 to 0.88, axis 0.56 to 0.62.
24 redimita W. G. Binn. Wh. (4½) 5½ to 6, reddish brown, band single, umbil. small or none; (var. of 25?) diameter 0.80, axis 0.48.
XI Group. (Arianta and Aglaia part., auct.) Form much like Arianta arbustorum, sculpture like last. Umbilicate.
25 Nickliniana Lea. Wh. 6 to 7, yellowish-brown, oblique grooved, wrinkled or malleated, umbil. small; diam. 0.72 to 1.05, axis 0.42 to 0.80.
26 Bridgesii Newc. (Not of Tryon, 1866.) Wh. 6, grayish corneous, thinner, band broader, umbil. wider than 25 (a var.?); diam. *1.00, axis 0.73.
27 arrosa Gld. Wh. 5½ to 7, brown, mottled yellow, (vars. yellow or olive, bandless) wrinkled malleate; diam. 1.10 to *1.60, axis 0.59 to 0.90.
28 exarata Pfeiff. (Not of Weigm. = cælatura Fer.) Wh. 6 to 7, yellow, or olive and brown mixed, strongly wrinkled, faintly malleate; diam. 0.75 to 1.15, axis 0.40 to 0.62.
29 ramentosa Gld. Wh. 5½ to 6½, yellowish brown, thin, oblique grooved, sometimes wrinkled; diam. 0.70 to 1.30, axis 0.57 to 0.90.
30 reticulata Pfeiff. “Wh. 5½, reddish brown, band single, sculpture like 29,” (probably a var.); diam. *0.85, axis 0.47.
31 tudiculata Binn. Wh. 5 to 5½, brown or olive, band wide, paler margined, malleate, body whorl swollen; diam. 0.90 to 1.40, axis 0.45 to 0.80.
XII Group. (“Polymita” Tryon, part, “Arianta” Albers. part.) Sub-globose conic; axis, 0.6 to 0.8 diam.; band single, obscure, or none, often mottled; smooth or with revolving grooves, sub-imperforate. Usually paler below.
32 Kellettii Forbes. Wh. 5, reddish with pale mottling in bands, faint revolving or oblique grooves; diam. 0.72 to 1.20, axis 0.48 to 0.68.
33 crebristriata Newc. Wh. 5, dark corneous, band obscure or none, lip sometimes continuous; diam. *0.92, axis 0.55 to 0.80.
34 intercisa W. G. Binn. Wh. 5, grayish or brown, band obscure, deeply grooved, lip thick, continuous, tubercled; (= 33 var.?) diam. *0.84, axis 0.57. “Hab. probably San Miguel I.” Newcomb, from worn specimens in his museum, not “Oregon.”
35 Tryoni Newc. Wh. 5½ to 6, bluish or mottled, pale below, band faint, lower lip sometimes tubercled; diam. *0.80, axis 0.55.
36 Carpenteri Newc. Wh. 5½, brownish white, band faint, fine revolving grooves, mouth subcircular; diam. *0.90, axis 0.64.
37? Rowellii Newc. “Wh. 4½, opaque white, no band, or sculpture” (bleached?), mouth subcircular, umbilicate; diam. *0.60, axis 0.40. (Unique specimen, and may be of the Mexican group, like lævis, etc.)
“Arianta” Remondii Tryon, and “Galaxias” griseola and Berlandieriana, of Mexico, seem to connect this group with the next.
†† Band triple, colors strongly defined.
XIII Group. (Aglaia Alb. part.) Generally lower than group XII, and lip more expanded, umbilicus large or moderate, with revolving grooves, or smooth.
‡ Colors light, often palest below. Inhabit dry or treeless regions, from lat. 32° to 36°.
38 facta Newc. Wh. 5 to 5½, white, or brownish above, lip yellow, umbil. nearly covered; diam. *0.42, axis 0.22.
39 Gabbii Newc. Wh. 5, band margins and grooves obsolete; (unique, between 38 and 40;) diam. *0.40, axis 0.20.
40 rufocincta Newc. Wh. 5 to 6, pale brown, depressed, umbil. moderate, lip broad; diam. 0.50 to 0.85, axis 0.22 to 0.45.
41 Traskii Newc. Wh. 6 to 6½, like last, but umbil. larger, lip thinner, usually higher; diam. 0.90 to 1.00, axis 0.40 to 0.62.
42 Ayresiana Newc. Wh. 6 to 7, yellowish, paler below, strongly grooved, spire elevated; diam. *0.80, axis 0.55. “Santa Cruz I., Cal.” Newcomb coll.
‡‡ Colors dark, often paler above. Inhabit damp coniferous forests, lat. 37° to 50°.
43 Dupetithouarsii Desh. Wh. 7 to 8, brown or olive, band margins whitish, grooves obsolete, often submalleate; diam. 0.90 to *1.20, axis 0.54 to *0.60.
44 fidelis Gray. Wh. 6½ to 7, band and beneath black, band margins and above red or yellow (a hybrid? var., black, and becoming slightly angled); diam. 1.12 to 1.50, axis 0.60 to 0.90. “Oregonensis” Lea, may be = 44 jun.
XIV Group. (Aglaia Albers, part.) Depressed, usually subangled, hirsute or bristle marked, umbil. large.
45 infumata Gld. Chestnut to black, a single band sometimes visible, angled, lip thin, bristles deciduous; (closely allied to black var. of 44;) diam. 1.40 to *1.50, axis 0.54 to 0.60.
46 sequoicola Cp. Wh. 6½, dark brown, rounded, bristles only in young, leaving marks; diam. *1.08 to 1.20, axis 0.50 to 0.54.
47 Mormonum Pfeiff. Wh. 6 to 6½, brown, depressed, sometimes subangled, sometimes bristle marked; diam. 0.95 to 1.30, axis 0.50 to 0.54.
48 Hillebrandi Newc. Wh. 6, yellowish brown, bands hid by persistent long bristles, subcarinate, lip broad; diam. 0.80 to 0.96, axis 0.35 to 0.40.
C. Bandless; lip more developed, reflected, often toothed at the base.
Genus Mesodon Raf. Lip broadly expanded, often 1-3 toothed, or with parietal tooth only, sometimes none; corneous.
XV Group. (“Arianta.”) Toothless, umbilicus large, surface coarsely wrinkled or granulate, lip broad, reflexed.
49 Townsendiana Lea. Wh. 5½, to 6, mixed yellow and brown, body whorl coarsely wrinkled, fine revolving grooves; diam. 0.68 to 1.38, axis 0.35 to 0.55.[35]
50 anachoreta W. G. Binn. “Wh. 6, reddish ashen, granulated and sparsely indented;” diam. *1.00, axis 0.54.
XVI Group. Odotropis Raf. “Tooth upon columella, umbilicus covered.” Lower lip tuberculate, and a parietal tooth.
51 devia Gld. Wh. 6, brown or olive, no sculpture except distinct lines of growth; diam. 0.80, axis 0.45.
XVII Group. Aplodon Raf. One parietal tooth, (or none) perforate or imperforate, hirsute or smooth, lip simple.
52 Columbiana Lea. Wh. 5½ to 6, corneous brown, with or without hairs, umbilicate; diam. 0.50 to 0.70, axis 0.25 to 0.35. The small imperforate and toothed form usually classed with this species may better be considered a rounded var. of germana, the subangled form of which is very rare.
53 germana Gld. “Wh. 5½, reddish corneous, hirsute, subangled, one parietal tooth, imperforate;” diam. *0.30, axis 0.20.
XVIII Group. Triodopsis Raf. “Umbil. large, a tooth on each lip, and one parietal.” Sometimes hirsute, hairs deciduous.
54 Mullani Bld. Wh. 5½ to 6, brownish corneous, microscopic spiral lines and tubercles; (hairy?) diameter *0.53, axis 0.29.
55 loricata Gld. Wh. 5½, brown or greenish, scale-like wrinkles quincuncially arranged; diam. *0.25 to 0.35, axis *0.10 to 0.20.
I am indebted to Dr. Newcomb and Mr. R. E. C. Stearns for much assistance in preparing this paper. Though not offered as a final arrangement of the species, it is hoped that this synopsis may aid in their determination, and thus make a step towards a correct systematizing of this difficult series.
There are four or five other subgenera among the 50 species of this family in the Atlantic States, divided by Bland into fifteen groups. He places Nos. 51, 54, and 53 in his 8th, 9th, and 15th groups respectively.—(Ann. N. Y. Lyc. N. H. 1864.)
[32] Extreme specimens of H. arrosa found by Mr. Gabb in Mendocino County, Cal., its northern limit, and also one of H. redimita found in Alameda County by Mr. Holder, have exactly the form of H. pomatia, and in each case have one and a half whorls less than the types, indicating perhaps that the usual forms found here are higher developed than the type of the genus. (A genus Pomatia has also been founded on this type of the Linnæan genus Helix.)
Aglaia was used by Escholtz, 1825, in Acalephæ, by Swainson, 1827, in Birds, and by Renier Philinidæ, before Albers adopted it in this order!!
[33] See, also, the “Geographical Catalogue of West Coast Mollusca,” published by the State Geological Survey, April, 1867.
[34] The west slope specimens may be all of species 20.
[35] A specimen figured by Mr. Tryon in the last number of the “Journal” just received, (May, 1867), as “var. minor,” from Idaho and Nebraska, seems to have an obscure band, which, together with its form and want of wrinkles, indicate entire distinctness from Townsendiana. The small form of the latter found by me in Montana has no band, and seems close to Binney’s anachoreta, of which supposed specimens from “Oregon” are in Mr. Rowell’s collection. The Eastern Mesodon clausa, elevata and perhaps others, have been found banded occasionally, but without the paler margins, and only as an exception.
Prof. W. P. Blake read the following: