OP CONCirOLOGY, 331 



Pupa (Modicella) Arizoxexsis, Gabb.— Plate 21, fig. 6. 



Description. — Shell small, resembling P. marginaia. Say, [P. 

 fallax, Gld.,) but more robust, sides more parallel, and apex 

 more convex; imperforate, fusiform; sides diverging convexly 

 from the apex, afterwards becoming more nearly parallel ; 

 whorls 5|, convex ; suture deeply impressed ; lines of growth 

 barely visible with a lens; color light horn, shining, shell 

 translucent ; aperture suboval, edentate ; lip thickened, strong- 

 ly reflected, white, opaque, acute externally, not constricted 

 behind the reflexion; peristome not continuous on the body 

 whorl ; a slight emargination exists on the inner edge of the 

 peristome, near the posterior end of the outer lip. 



Dimensions. — Height -18 in., width of body whorl '09 in., 

 length of aperture -06 in. 



Locality. — With the preceding. (Dr. Horn.) 



Observations. — This shell resembles more nearly, P. margi- 

 nata, Say, than P. modica, with which it is also related, but 

 can be distinguished from both by its more truly Pupoid shape, 

 by the mouth being more distinctly angulated near the poste- 

 rior end of the outer lip, and by the peculiar emargination of 

 the internal edge of the peristome. 



Pupa hordacea, Gabb. — Plate 21, fig. 7. 



Description. — Shell very small, cylindrical ; apex obtuse ; 

 whorls 6, convex; suture well impressed, smooth, thin, horn- 

 color ; aperture small, rounded below, unarmed, lip narrowly 

 reflected and white; base umbilicate, the umbilicus bounded 

 by an angle. 



Dimensions. — -Length '11, width "04 inch. 



Locality. — With the preceding. 



