50 LIXN^AN GENERA. 



Many of the Cones are very beautiful. Some of them bi-ing the 

 highest prices of all shells, from their great rarity. One species, the 

 Cedo Nulli of Lyonet, is valued at one hundred guineas. Cones are 

 covered with an epidermis, and it is not till this is removed that their 

 beauty can be seen. Their surface is highly pohshed, contributing 

 much to heighten the delicate and glowing tints vihich are diffused 

 over some of the finer species in an infinite variety of undulations, 

 clouds, spots, and bands. 



Genus 21 — CYPR^A. 



Animal a Slug ; shell univalve, involute, sub-ovate, 

 smooth, obtuse at each end; aperture effuse at both ex- 

 tremities, linear, extending the whole length of the shell, 

 and dentated or toothed on each side. 



Linnaeus divides the genus Cypraea into four families : *mucronate, 

 or pointed ; **obtuse, and without any manifest spire ; ***mnbili- 

 cated, or with a small perforation ; ****marginated. 



The genus Cj-pi'sea consists of beautifully coloured, and very highly 

 poUshed shells. It is said, that they leave their shells annually, and 

 construct new and lai'ger ones. But we have not been able to ascer- 

 tain this point as a fact. 



They live in sand at the bottom of the sea ; the animals are provided 

 with a membrane, which they throw over their shells, and which pre- 

 serves the tine polish, and prevents other testaceous bodies from fixing 

 on them. The Cypriese have only been found to inhabit the ocean. 



Cyprcca Uropcea The European Ctpr^a. Plate 



VIII. fig. 21. With numerous transverse furrows, tumid 

 on the back, pale purple or whitish, and generally with 

 three dark blackish-brown spots. Half an inch long. In- 

 habits the British seas. 



Genus 22 BULLA. 



Animal a Lim.ax; shell univalve, convolute, and unarmed 

 with teeth ; aperture a little straitened, oblong, longitudinal, 

 very entire at the base ; pillar oblique and smooth. 



Bulla Catena. — The Chain Bulla. Plate VIII. fig. 

 22. (Bullsea Catena, Lamarck.) Ovate, white, pellucid, 

 with minute chain-like transverse striae ; aperture extremely 

 large, obtuse at the top, with a single volution, and one- 

 fourth of an inch long. Inhabits the British seas. 



