Bulla Haliotoidea.—Sigaretus — Cryptostoma. 427 



BULLA HALIOTOIDEA, Mont. 



The examination of a nnmber of specimens of this shell with its 

 animal, prove that it should be considered as a Sigaretus, accord- 

 ing to Cuvier, (see his Memoires pour servir a VHistoire et a 

 VAnaiomie des Mollusques, published in the Annates du Museum 

 d'Histoire Naturelle;) inasmuch as it accords exactly with his 

 description and figures there given. It is well known that the 

 shell has no canal at the base of the aperture ; the most singular 

 circumstance therefore, in this animal, is that a fold in the large 

 membranous mantle, serves both the purposes of the shelly and 

 of the membranous canal in the Buccinidw, while in its general 

 structure it otherwise resembles the animals of that family ; the 

 sexes being separate and distinguished easily by the male organ 

 proceeding from the back of the neck. Of about twelve specimens 

 that came under my examination at one time, two only were 

 males. G. B. S. 



ON THE GENERA SIGARETUS AND CRYPTOSTOMA. 



Adanson in his Voyage to Senegal mentions by the name of 

 Sigaret, a shell of which he had not seen the animal ; Lamarck, 

 however, having specimens of what he considered as the same 

 shell, from the same place, and with the animal, sent them for 

 examination to the celebrated Cuvier, who described the animal 

 in the 31st number of the Bulletin des Sciences; whereupon La- 

 marck in his Systeme, formed it into a genus under the name of 

 Sigaretus, referring to Cuvier for the description of the animal and 

 to Adanson for that of the shell. It is, nevertheless, observable, that 

 Cuvier in his Memoirs on the Anatomy of Mollusca, has described 

 and figured under the same name an animal, which he received 

 from the Isle of France, very different from that which he de- 

 scribed before, and whose shell is also different from Adanson's 

 Sigaret, being pellucid, and very nearly allied to Bulla haliotoidea 

 of British Authors ; whose animal Montagu considered as forming 



