MONOGRAPH OF THE GENUS 



CYPILEA. 



Char. Gen. Molluscum gasteropodum, testam spiralem 

 inter lobas pallii partim velans. Testa convoluta, ovato- 

 subpyriforniis vel subcylindracea, polita, interduin tubercu- 

 lata vel costellata ; spira, brevissima, omnino aut partim 

 caslata; apertura angusta, ad terminos testa? extensa, in ca- 

 nalem brevem utrinque terminanti, columella incrassata, ad 

 marginem internum transverse denticulata, plus minusve 

 longitudinaliter angulatim depressa, antice excavata, plerum- 

 que plica conspicua desinente ; labio inflexo, incrassato, 

 transverse dentato. — Shell convolute, ovately piriform or 

 subcylindrical, polished, sometimes tuberculated or ribbed ; 

 spire very short, partially or entirely concealed ; aperture 

 narrow, reaching to the extremities of the shell, terminat- 

 ing at each end in a short canal; columella thickened, 

 transversely denticulated at the inner edge, more or less 

 longitudinally angularly depressed, excavated in front, ge- 

 nerally ending in a conspicuous plait ; outer lip inflected, 

 thickened, transversely toothed. 



The genus as above described, including the Trivice, is 

 not liable to be confused with any other. In one character 

 it is approached by the genus Ovulum, namely, in the in- 

 flected outer lip. But Ovulum has no system of transverse 

 teeth on the base, and is otherwise easily distinguished. 



Two species of Ci/prcea, namely, 0. edentula and C. leuco- 

 storna, are almost toothless, but they are otherwise allied 

 closely to species having the usual system of teeth. 



In attempting to arrange the Cypraa in groups according 

 to their affinities, it is very difficult to find any leading prin- 

 ciple of association or separation, because shells associated 

 by one set of characters are dissociated by others. Thus, 



