251 



CASSIDARIA. 



BUCCINUM ECHINOPHORUM. Linn. 



Mart.% t. 41,/ 407, 408. 



The shells of this genus are nearly allied to the G. Cas- 

 sis, but some striking differences of character render 

 their separation necessary. They are in general more 

 inflated and rounder than the G. Cassis, but what 

 principally distinguishes them, is, the canal which 

 terminates the lower part of the aperture not being 

 suddenly recurved towards the back of the shell, but 

 ascendant and very little arched ; the spire is short, co- 

 noid, composed of convex whorls, without any thick- 

 ened bands; the left margin apparent, and affixed to 

 the columella, which is almost always covered with lit- 

 tle rough, oblong, transverse tubercles ; right lip plait- 

 ed or thickened; exterior transversely grooved, and the 

 upper part of the whorls, in some species, with small 

 round tubercles, regularly placed. They are marine 

 shells. 



Cassidaria echinophora Cassidaria cingulata 



Thyrrena striata 



Cassidaria oniscus. 

 [There are also two fossil species.] 



