TIIK NAUTILUS. 141 



Columbia, I'a. 



About tliirty specimens of tliis amnicola-sliaped species were in (lie 

 collection of tlie late Dr. G. A. Lothrop,, labelled Amnicola decisa, 

 but unfortunately with no indication from whom they were obtained. 

 The large number of species from that locality in the collection would 

 indicate that Dr. Lothrop had been in correspondence with some col- 

 lector residing in that vicinity. At first sight, it would be taken for 

 an Amnicola, but the columellar callus is decisive on its generic posi- 

 tion, which is confirmed by the allied S. virginicus and by Mr. 

 Hinkley's discovery of a somewhat similar elevated form (S. Irink- 

 teyi) in the Coosa. It is similar in shape to that form, but is smaller, 

 the whorls more rounded, the columellar callus is narrower and 

 rounded, and there is no decided angle at the junction of the basal 

 lip with the columella. In shape it resembles also somewhat S. 

 virginicus but differs in the particulars pointed out in connection with 

 that species. 



Somatogyrus virginicus n. sp. PI. v, figs. 17, 18 and 19. 



Shell small, globosely conic, imperforate, light greenish-yellow, 

 smooth, shining, lines of growth very fine. Spire elevated, obtusely 

 conic. Whorls about 4, those of the spire convex, with a well- 

 impressed suture, body whorl subglobose, regularly convex. Aper- 

 ture ovate, angled above and broadly rounded below. Umbilical 

 region impressed, but covered by a rather broad, rounded columellar 

 callus which becomes thinner and transparent on the parietal wall. 

 Columella nearly straight. Lip thin and sharp. Alt. (fig. 18) 3|, 

 diam. 3 mm. Alt. (fig. 17) 3^, diam. 2^ mm. 



Barnard's Ford, Rapidan R., Va. (W. J. "Fairer Coll.) 

 This species in its elevated form resembles S. pennsylvanicus, and 

 the two with S. hinkleyi form a natural group quite distinct in shape 

 from all the other known species. It differs from the latter in its 

 smaller size, more convex body whorl and narrow, rounded colu- 

 mellar callus, and from the former in being somewhat larger, less 

 solid, more globose, thin lip, color and especially in the impressed 

 umbilical area, which is one of the most distinctive specific charac- 

 ters. Like many of the Amnicolte, there are two forms represented 

 in the series, one being decidedly more slender than the other as 

 shown by the figures, otherwise they are entirely similar. This is 

 probably a sexual difference, but has not been observed in any other 

 species of this genus. 



