OF CONCHOLOGY, 311 



ZOOGENITES, Morse. 

 1. Zoogenites harpa, Say. 



Plate 15, figure 1. 



Ovate-conic, apex acute, thin, translucent, covered witli sharp, 

 thin, blade-like longitudinal ribs, apex acute and smooth, whorls 

 four, convex, with impressed suture ; aperture large, obliquely 

 semi-circular, without teeth, lip not reflected ; umbilicus minutely 

 perforated. Light horn color. 



Length 5, diam. 3'5 mill. 



Maine to Iowa. 



This is a boreal species, and has not been met with south of 

 the above localities, 1 believe. It much resembles, except in size. 

 Helix Idahoensis, Newcomb. 



Family CYLINDRELLID^. 



Shell cylindrical, multispiral, truncate, frequently costate ; 

 aperture small, subcircular, edentuous, peristome expanded, con- 

 tinuous. 



CYLINDRELLA, Pfeiffer. 



Subgenera. 



GoNGYLOSTOMA,' Albers. — Cylindrically fusiform, apex attenuate, 

 costulate or striate, Avhorls f) — 20, the last more or less pro- 

 tracted, obsoletely angulate ; aperture circular, lip expanded. 



HoLOSPiRA, Albers. — Shell turrited or fusiform, apex conical, not 

 truncate ; whorls 11 — 14, the last not protracted, base cari- 

 nate ; aperture subquadrangular, peristome expanded, colu 

 mella plicate. 



Genus GONGYLOSTOMA, Albers. 

 1. Gongylostoma Poeyana, PfeiiFer. 



Plate 15, figure 27. 

 Elongate, thin, longitudinally sharply striate ; spire very long, 

 acuminate and truncate at the apex ; whorls eleven, slightly con- 



