4iG PROCEEDINGS OF THE ACADEMY OF 



TERTIARY SPECIES. 



GASTEROPODA. 

 Genus VIVIPARA Lamarck. 



VlVIPAKA RAYNOLDSANA. 



Shell, large, ovate ; spire rather elevated, pointed at the apex ; volution 

 about six and a half; ventricose, increasing rather gradually in size, some- 

 times a little compressed around the middle, so as to present a slightly shoul- 

 dered appearance above ; last one often prominently rounded or iaintly sub- 

 angular a little below the middle ; suture well defined ; aperture broad sub- 

 ovate or subcircular ; columella scarcely perforate. Surface of upper whorls 

 usually smooth, or only marked by very obscure lines of growth, which 

 generally become quite strong near the aperture, and on the under side of the 

 body whorl. On the last two volutions of well preserved specimens, more or 

 less distinct threadlike revolving striae are usually seen, which are rarely con- 

 tinued upon the succeeding turns above ; generally two or three of the revolv- 

 ing lines on the middle of the whorls are larger than the others. 



Length, 1"56 inches; breadth, 1*14 inches; apical angle convex; diver- 

 gence 60 to 65. 



In size and general outline, this fine Vivipara resembles our V. Leidyi, ( = 

 Paludina Leidyi, Proceed. Acad. Nat. Sci. Phila., June, 1S56, p. 123), but it 

 differs in having much more convex whorls and a deeper suture. It also 

 differs from that species in always having its revolving lines most strongly 

 defined on the lower whorls, while those of V. Leidyi are entirely confined to 

 the upper turns near the summit of the spine. 



From our V. Leai, (=Paludina Leai, Proceed. Acad. Nat. Sci. Phila., June, 

 1856, p. 121), it will be readily distinguished by its larger size, proportionally 

 more elevated spire, and more or less distinct revolving lines. It also differs 

 in having its whorls usually a little compressed around the middle, so as to 

 give them a slightly shouldered appearance above. This latter character and 

 the revolving lines are not, it is true, always distinctly marked, but when 

 they are not, its more attenuate spire and larger size, will alone always serve 

 to distinguish it from V. Leai. 



Amongs' recent species it is represented by such forms as V. Burroughiana 

 Lea, and V.carinata Val. It is longer, proportionally thicker, and has a more 

 elevated spire, than the first ; and differs from the latter not only in being 

 much longer, but in always having less angular whorls. Its aperture is also 

 rounder, and less extended below than in V, carinata. 



Named in honor of Captain Wm. F. Raynolds, U. S. Topographical En- 

 gineers. 



Locality and position. Lower fork of Powder River, Fort Union or Great 

 Lignite Group. Tertiary. 



Genus HELIX Linnasus. 



Helix spatiosa. 



Shell large, rather thin, subdiscoidal, the spire being depressed, but not 

 flat ; umbilicus about half to two-thirds the breadth of the outer whorl at the 

 aperture, deep, conical, and showing near one-fourth of each volution of the 

 spire ; whorls five and a half to six, increasing gradually in size, somewhat 

 depressed and sloping outwards above, narrowly rounded, or (in young speci- 

 mens) subangular around the periphery, compressed <onvex below, and 

 rounding abruptly into the umbilicus on the inner side ; suture moderate! v 

 distinct ; aperture transversely snboval, being a little wider than high, and 



[Dec. 



