66 Lamavck's Genera of Shells. 



dilated, sometimes only one ; and again, sometimes neither of them 

 are prominent or inflated. 



Lamarck states that observation has proved that the animal of 

 the cypraea continues to grow after it has completed its shell, 

 which it is consequently obliged to quit, and form a new one ; 

 hence the same individual may form several shells with a single 

 layer of testaceous matter, and several with the layers double, or 

 complete ; and this he thinks is proved by the fact that perfect 

 shells of the same species are often found of different sizes. 



The head of the animal which inhabits the cypraea, is furnished 

 with two slender conical tentacula, finely pointed, with the eyes 

 situated near the base on the outer side. The tube for re- 

 spiring water is short, and placed on the neck ; it is formed by 

 the anterior part of the mantle, and lodged in the notch of the 

 shell which terminates the aperture on the side next the spire. 

 The foot of the animal is a ventral, fleshy, linguiform disc, which 

 it uses for the purposes of locomotion. 



The cypreese live buried in the sands, at some distance from the 

 sea coast, both in hot and temperate climates. The different 

 species, which are very numerous, are not easily distinguished 

 from each other, for their individual characters, independent of the 

 colours of the shell, are few. 



Type. Cyprcea cervina*. (Cypraea oculata. Gmel.) 

 Shell ovate-ventricose, yellow or chesnut colour, sprinkled with 

 small, very numerous, whitish spots ; longitudinal dorsal line 

 straight, light coloured ; interior of the lip inclining to violet. 

 American Seas. PI. v. Fig. 204. 6» ecent species, and 18 

 fossil. 



3. Terebellumf. 

 Shell convolute, subcylindrical, pointed at the summit. Margin 

 simple, and acute. Aperture longitudinal, contracted at the upper 

 part, notched at the base. Columella smooth, truncated at the 

 bottom. 



The genus bulla, observes Lamarck, seems to have been a pro- 



* Belonging to a stag, from the colour of the shell. f A little auger. 



