85 



Genus 24. CASSIDARIA, Lamarck. 



Animal ; disc large, oval, slightly truncated in front, with a small 

 oblong horny operculum near the posterior part ; head large 

 and thick, prolonged into a pair of elongated tentacles, at the 

 base of ivhich are the eyes ; proboscis cylindrical, rather long ; 

 respiratory siphon of only moderate length. 



Shell ; oval, ventricose, contracted towards the base and attenuated 

 into a curved canal which is reflexed posteriorly ; columella 

 lip smooth and expanded over the body whorl; outer lip 

 reflected, sometimes crenated. 



The Cassidarice, distinguished originally by De Montford under the 

 title of Morio, and which name according to the strict rules of priority 

 should have been adopted, differ principally from the Cassides in the light 

 inflated growth of the shell, with its contracted, attenuated structure 

 towards the base, and recurved folding canal ; they approximate in tins 

 respect to Cassis, partaking somewhat of the character of Bolium, for not 

 only is the shell distinguished by the same tenuity as the latter genus, but 

 there is some affinity in the soft parts, to judge by the ample growth of the 

 disk, and length of the proboscis. 



The Oniscia were referred to the genus Cassidaria by Lamarck, but 

 their shell is uniformly of smaller size, and of more solid growth, indepen- 

 dently of its granulated columella and other characters just observed under 

 that head ; it is likewise highly probable that a difference will be found in 

 the animal of Oniscia of sufficient generic importance to confirm the pro- 

 priety of its beiug adopted. 



Of the following half dozen species hitherto recorded I am only ac- 

 quainted with three, and of these, C. striata, Tyrrhena, and ec/iinophora, 

 the last two are regarded by some authors as varieties ; I have no doubt, 

 however, myself, of their specific difference. 



Species. 



1. acuta, Gray. 3. Deshayesii, Duval. 5. striata, Lam. 



2. cingulata, Lam. 4. echinophora Lam. 6. Tyrrhena, Lam, 



Figure. 



Cassidaria Tyrrhena. PI. 6. Fig. 31. Shell, showing the aperture, re- 

 curved folding canal, and expanded columellar lip. 



