166 Panama Shells. LITTORINID^E. 



and of which the remainder cover the anterior part of the last 

 whorl : apex very minute : spire with the outlines nearly rec- 

 tilinear : whorls eight, more or less angular in the upper part, 

 with a well impressed suture ; last whorl rather long, with a 

 well rounded periphery : aperture subovate : labrum thin : 

 columella rather stout : umbilicus wanting. 



Mean divergence about 16 ; length .13 inch ; breadth .04 

 inch ; length of spire .1 inch. 



Station. Unknown. 



Habitat Panama ; C. B. A. ! 



10 specimens, in various stages of growth, were collected from 

 the sand. 



223. Chemnitzia commimis. Nov. sp. 



Shell long, fusiform conic : dingy white : with, on the penult 

 whorl, about twenty-two transverse ridges, and on the last whorl 

 a greater number, which are less prominent, and which become 

 obsolete anteriorly : with spiral ridges, of which four or five are 

 seen on the spire, and which on the last two whorls are as pro- 

 minent as the transverse ridges, but above are less developed : 

 apex with the axis oblique : spire with the outlines curvilinear : 

 whorls eight, moderately convex, with a well impressed suture: 

 last whorl rather long: aperture ovate, acute above, very 

 broadly effuse below : labrum rather thin, but not sharp : colu- 

 mellar lip well thickened, below reflected over a minute umbili- 

 cal indentation : columella with one small plait. A large speci- 

 men has the following dimensions : 



Mean divergence about 23; length .165 inch; breadth .05 

 inch ; length of spire .11 inch. 



Station. Under stones near low water mark. 



Habitat. Panama and Taboga ; C. B. A. ! 

 90 specimens were collected. 



