CALYPTR^A. 



TESTA conoidea, vertice subcentrali, imperfd-* 

 rato ; basi plus aut minus i*egulariter orbiculata, 

 Integra, acut^. Cavitks appendice laterali; iii^ 

 terno, adnato, vel cyathiformi, tel convolute-* 

 linguiformi, vel septum spirale efformante. 



Part of the Linnean Patellae coristitute the Lamarckiaii 

 Genus Calyptrcea, which, with several other very different 

 genera, such as Emarginula, Fismrella, Pileopsis, include 

 ing Hipponyx, forms his family of Calyptraciens, Al- 

 though the animal is tinknovrn, he thinks, judging from 

 the inner part of the shell, that it cannot he related to 

 that of Patella; and that the internal appendage is an 

 indication of structure approaching to that of Ttochus, 

 and concludes that the Patella trochiformis is better placed 

 among the Trochi than in this Genus : tve must, how- 

 ever, beg leave to differ froili hiiti, and consider the 

 P. trochiformis as a decided Calyp)trcea, inasmuch as the 

 spiral inner lip is entirely covered by the animal , and as 

 it has no operculum. In considering the characters of 

 this Genus, we felt some repugnance to the union of 

 shells whose inner lips assume so many different forms 

 under one generic name; but ah examination of a great 

 number of species has convinced us that it would be 

 impossible to separate them, unless, indeed, we were to 

 constitute a particular Genus for evei'y variation in form, 

 in which case we think the number of genera would be 

 unnecessarily augmented. Calyptrcea and Crepidula ap-- 



