p. 323-325 : ill. ; 24 cm.Includes bibliographical references

Cockerell, Theodore D. A. (Theodore Dru Alison), 1866-1948.

Stein, William, paleontologist.

American Museum of Natural History Scientific Publications

564,38(118: 78.7)Article XXIV.- LAND SHELLS FROM THE TERTIARY OFWYOMING.BY T. D. A. COCKERELL.In 1912, Mr. W. Stein collected for the American Museum of NaturalHistory a quantity of small land shells near the mouth of Pat O'Hara Creek,in Clark's Fork Basin, Wyoming. A study of this material reveals a sur-prising number of species, eight in all, and shows that shells apparentlyreferable to the Indian genus Boy&ia, and to a new allied genus, inhabitedthe Rocky Mountain region in early Tertiary times. One of the new spe-cies collected by Mr. Stein was described in this Bulletin, XXXIII, p. 105;four others are described herewith.It is extremely desirable that further material should be collected atMr. Stein's locality, so rich in remarkable species, on the whole in an ex-cellent state of preservation. It is surely probable that we have only aportion of a quite rich Molluscan fauna.Protoboysia n. g. (Bulimulidae.)Shell conic-globulose, with an obtuse regularly rounded spire of seven flattenedwhorls; eighth whorl curved upwards, obliquely wrapping the spire, curving roundit near the apex, the narrowly semilunar aperture situated on the sides of whorls3 to 6; near the point where the last whorl ascends is a deep transverse constriction,the margins of which are thickened. The sculpture consists of fine oblique stria,coarser on the last whorl. The nuclear region appears to be without sculpture.The umbilicus is represented by a chink. Type, P. complicata n. sp.Protoboysia complicata n. sp. (Fig. 1; A, side view; B, from beneath.)Length and width 3' mm.; oblique striaw regular,about 6 in 160 , near end of seventh whorl, fine and f'\'(ii,5widely spaced (95-125 M apart) a short distance before ; 4aperture.Five miles southeast of mouth of Pat O'HaraCreek, Clark's Fork Basin, Wyoming. Above red-banded beds; probably base of Wasatch formation.' Fig. 1. Protoboysia cam-(W. Stein, 1912). plicata.This is a most astonishing discovery; a shell entirely new to our AmericanTertiary, closely resembling the Indian Boysia bensoni Pfeiffer, but with the'See, however, Granger, Bull. Amer. Mus. N. H.. XXXIII, p. 204.323Bulletin American Museum of Natural History. [Vol. XXXIII,last whorl even more wrapped around the spire, and showing toward thebase a swelling followed by a deep constriction. The last feature reminds usof the Brazilian Tomigerus cumingi Pfeiffer, which is perhaps the nearestrelative of our shell in the New World. Pilsbry (Non-Marine Mollusca ofPatagonia, Rep. Princeton Univ. Exp. to Patagonia, III, p. 619) has givenmaps showing the scattered distribution of this group of molluscs in theNeotropical Region; while we have the remarkable case of the genusHyperaulax, which has a living species on the island of Fernando Noronha,and several fossil representatives in the Silex Beds at Tampa, Florida.The discovery of a member of this group in the Tertiary of Wyoming affordsone more illustration of the former occurrence in the north of a type nowmore southern on both sides of the world.Boysia Pfeiffer, 1849.The two following species are without the callus and constriction at thebeginning of the ascending whorl, and cannot at present be distinguishedfrom Boysia.Boysia sinclairi (Cockerell). (Fig. 2, showing broken aperture.)Gastrodonta (?) evanstonensis var. sinclairi Cockerell, Bull. Amer. Mus. Nat.Hist., XXXI, (1912) p. 231.The upturned whorl had been broken off in the type; but numerousspecimens found with Protoboysia clearly show that thelast whorl was directed upwards, very narrowly crescenticin section, to end on the fourth to sixth whorls in anaperture provided with a very thick reflexed lip. . Onlythe upper end of the lip has been preserved, so the formof the aperture cannot be ascertained. The whole shell,sia sinclairi. except the apex, has delicate oblique riblets.Boysia phenacodorum n. sp. (Fig. 3.)Shell subglobose, about 5' mm. high and 7 broad; spirerounded and obtuse, with six very slightly convex whorls, whichare distinctly obliquely striate, the sixth having coarse regularribs, five to a mm.; the last, upturned whorl is only partly pre-Fig. 3. Boysia served, but appears to be formed as in B. sinclairi, except that itphenacodorum. is not so narrowly crescentic in section. The umbilicus is closed.324Cockerell, Tertiary Land Shells from Wyoming.Two specimens, found with Protoboysia. Easily known from B.sinclairi by its smaller size and less elevated spire.Vitrea sinoparum n. sp. (Fig. 4.)Shell 5- mm. diameter, 24 high; spire low; whorls six, rounded, without distinctsculpture; aperture broad, somewhat oblique.Found with Protoboysia.A very modern looking shell, without striking Fig. 4. V'itrea 8i-characters. noparum.Thysanophora oxynse n. sp. (Fig. 5.)Shell not quite 5 mm. broad, 2- high; spire low; whorls 53, rounded, the lastwhorl elevated next to the suture; aperture semilunar, comparatively narrow;umbilicus broad.Found with Protoboysia. This is referred to Thysanophora with someconfidence, on account of its resemblance to the livingT. ingersolli of the Rocky Mountains; nevertheless, itmight belong to the Zonitidae, so far as the visiblecharacters show. Seen from above, it looks like Vitrea Fig. 5. Thysano-sinoparum. phora oxusnw.Other shells found with Protoboysia are Pyramidula ralstonensis Ckll.(many) and Oreohelix megarche C. & H. (immature).3251914.]

Tertiary land shells from Wyoming

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