NATURAL SCIENCES OF PHILADELnilA. 345 



an insufFicient comparative examination, specimens liave been dis- 

 tributed witli Mr. Say's name attached. 



Anachis ACUTA, Steams. 



Shell small, slender, acutely fusiform; spire elevated, pointed, 

 nucleus rounded, number of whorls eight ; in some specimens 

 sligldy convex and ti-aversed longitudinally by about 

 fifteen nearly equidistant prominent rounded ribs, which Fig. 3. 

 are absent on the apex and adjoining whorl, and become 

 obsolete just below the peripliery of the basal volution, 

 which is somewhat angidated below and at its anterior 

 portion marked distinctly with transverse costje ; in some 

 specimens the longitudinal ribs show a tendency to no- 

 dulation, and terminate rather abruptly upon the peri- 

 phery of the body-whorl; suture profound, cutting the 

 ribs abruptly- ; aperture one-third of the length of the shell, 

 whitish, narrowly ovate, angulate above ; outer lip simple, mode- 

 rately thickened ; slightly sliouldered and curved above, with 5-7 

 denticles within, which regularly decrease in size anterior!}' ; inner 

 lip showing a thin polished callus, with, in some specimens, a 

 slightly produced edge ; anterior canal short, moderately curved. 

 The shells of this species are quite variable in color, some indi- 

 viduals being of a porcellanous white, with transverse sienna lines 

 and lighter or darker blotches of the same color; others are of a 

 light sienna-yellow, with wliitish blotches and brown linear mark- 

 ings. The following are the dimensions of the largest and smallest 

 specimens : — 



Length .26. Length of aperture .09. Breadth .08. 



" .23. " " .08. " .09. 



Habitat. — West Coast of Florida, at Egmont Key, where several 

 specimens were collected by my friend E. Jewett, Esq. It seems 

 to be rather restricted in its distribution, and much less numerous 

 than A. avara or A. simplicata ; while the number of ribs is the 

 same as in A. avara^ the shell being much slenderer, these ribs are 

 much nearer to each other, and the surface is destitute of the re- 

 volving grooves which characterize that species. 



NiTiDELLA PiLOSA, Steams. 



Shell small, acutely conic, spire elevated, apex rounded; whorls 

 five, convex; suture distinct; surface white, traversed by nume- 

 rous equidistant fine revolving grooves ; bodj^-whorl one-half to 

 23 



