216 Proposed new Genus of Univalve Shells, 



It may be observed, in many species of Cyprse^a that, after 

 a certain age, the dorsal line which marked the division of the 

 two lobes of the mantle (so well exemplified in Cyprae N a 

 mappa) is obliterated, and that the basal edges become much 

 thickened. This is well exhibited in Cyprae v a caput ser- 

 pentis, vitellus, and most particularly in adult specimens 

 of caurica. In these cases, the mantle of the animal is in 

 precisely the same circumstances as in the typical species of 

 our genus; with this difference only : we suspect in Cyprae- 

 cassis the lobes of the animal never entirely enveloped the 

 shell, while in Cypraeva caurica, and others, the animal was 

 capable of enveloping the shell while it retained its cylindrical 

 form, but not after it began to expand laterally. 



The above specified distinguishing characters we think 

 quite sufficient to justify us in creating a genus for the re- 

 ception of that division of the genus Cassis denoted by the total 

 want of varices, the absence of an epidermal covering, and also 

 in being deficient of an operculum. 



The following species, abstracted from the genus Cassis, 

 will now form species of our genus CypRiECA'ssis, bearing 

 the same specific names. C. rufa Brugierc ; C. Masseuse 

 Kiener ; C. coarctata Valenciennes; C. testiculus Brugiere. 



It is our opinion, therefore, that this genus will stand in 

 much closer proximity to Cypra? v a than to Cassis. 



In the year 1826, the author met with specimens of C. rufa, 

 having the animal alive, among the reefs of the Paumotus, 

 South Pacific. They were in shallow waters, precisely in the 

 same circumstances as the Cypra^ae; namely, under large 

 stones, which not only protected them from their natural 

 enemies, but also from the burning rays of the sun. Since 

 then, his friend Dr. Cutting of Barbadoes has kindly ex- 

 amined the animal of C. testiculus, which, in conjunction with 

 the characters of the shell, fully corroborates these determi- 

 nations ; and, finding that in the late works of Blainville and 

 Kiener they still continue to be regarded as Cassides, he 

 hesitates no longer in making the division. 



In the beautiful work now in course of publication by L. 

 C. Kiener, entitled, Species general et Iconographie des Co- 

 quilles vivantes, there is a figure of the animal of Cassis 

 glauca; and this author refers to D'Argenville's Zoomorphose, 

 Adanson's Voyage au Senegal, MM. Quoy and Gaimard's 

 Voyage de V Astrolabe, and to Poli Sur les Coquilles de la 

 Sicile, for the anatomy of the animal of the genus Cassis ; 

 but they all refer to species typical of the Cassides as reformed 

 by this division. The genus Cypraecassis, like Cyprae'a, is dis- 

 tributed over a vast geographical area, but we are not aware 



