UNIVALVES. — CYPREA. 79 



Rubiginosa — Iron-mould. Angustata — Narrow. 



Miliaris — White-eyed. Similis — Black-spotted, 



Acicularis — Acicular. Striata — Striated. 



Crassa — Thick. Chinensis — Chinese. 



Vinosa — Claret. Pusilla — Small. 



BULLA. — Dipper or Bubble. 



Animal — a Limax: Shell univalvCf convolute, unarmed 

 with teeth: aperture a little straitened, oblong, longitu- 

 dinal, very entire at the base; pillar oblique, smooth. 



This genus, which contains fifty-two speciea, is in some 

 instances so nearly alhed to the preceding, that much 

 caution is necessary to prevent confusion in the classifica- 

 tion; so great indeed is the difficulty of distinguishing 

 the young shells of the Bulla and Cyprsea that the two 

 genera have been intermixed by some authors. How- 

 ever, one grand mark of distinction in this genus is, that, 

 in whatever stage of growth its species are found, they ne- 

 ver have teeth on both their lipsj the pillar-lip being in- 

 variably free from any appearance of denticulations; while 

 in the Cyprsese, both the pillar and outer lips are crenated 

 with very articulate and prominent teeth. There is also 

 a greater variety of form in the Bullae than in the Cy- 

 pr%8e. Some species, as the B. volva, or weaver's shuttle, 

 are of an elongated form, having the length much increas- 

 ed by two produced beaks : this shell, though far from 

 beautiful, is accounted a great rarity, and, when fine, 

 bears a high price. 



