164: Notes on certain Terrestrial Mollusca. 



levi ; sutiira profunda ; anfr. 4 convexi, lente accrescentes, ultimus latior, 

 rotundaius, antice vix descendens ; umbilicus -| diametri fere sequans ; 

 apertura obJiqua, rotundato-lunaris ; perist. simplex, rectum, marginibus 

 subconniventibus, coluraellari superne vix dilatato. 



Fig, 9. 



H. Mazatlanica Pfr. 



Shell umbilicate, sub depressed, thin, with oblique, rather dis- 

 tant rib-like striae, the interspaces microscopically striate, dark 

 horn colored ; spire convex, with smooth, obtuse apex ; suture 

 deep ; whorls 4, convex, gradually increasing, the last broader, 

 rounded, slightly descending above ; umbilicus about equal to 

 f the diameter of the shell ; aperture oblique, roundly lunate ; 

 perist. simple, straight, the margins approaching, the columellar 

 margin scarcely dilated. 



Diam. maj. 2; min. 15; alt. 1 mill. 



Habitat. — San Francisco, California. Rowell ! 



BemarJcs. — This small species is allied to H. asteriscus Morse, 

 and H. Mazatlanica Pfr., especially to the former; of both, to 

 facilitate comparison, I annex the figures executed for W. G. 

 Binney's work. 



H. conspecta differs from the former in having an elevated 

 spire and a smaller umbilicus. The rib-like striae are more 

 numerous, but scarcely raised above the surface of the shell, 

 which, under the microscope, is very similar to that of 

 asteriscus. 



The character of the striae and of the umbilicus sufficiently 

 distinguishes H. conspecta from H. Mazatlanica. For specimens 

 of H. conspecta I am indebted to Dr. !N"ewcomb and Dr. 

 Cooper. 



