41 



PILEOLUS, G. B. Sowerby. 



Gen. Char. Shell conical, with a subcentral, 

 upright vertex ; base concave, with a thin 

 margin and tumid centre; aperture small, 

 within the margin of the base, sublateral, 

 semilunar, its outer lip prominent, the 

 inner one crenulated; spire internal, very 

 short. 



1 HE form of the upper surfaces of the shells of this 

 Genus ii similar to that of Patella, for It is a short cone, 

 from the apex of which there are sometknes diverging 

 stri» or ridges ; the base also resembles Patella, in as 

 much as that it has a thin or sharp edge. Within this 

 edge is seen the transverse aperture leading to a very 

 short spire, that is wholly included within the cone, and 

 nearly fills it up in the form of a cushion. The aperture 

 is slightly curved and narrow, with parallel lips, and 

 rounded extremities ; the lips are separated, that near- 

 est the centre is crenulated. We suspect the spire is 

 reversed. 



The wholly internal spire, and the prominent outer 

 lip of the aperture, independent of the margin of the 

 base, are characters not possessed by any other genus of 

 involute shells. There are several points of resemblance 



Vol. V. /• „ ^ r 



