UNIVALVES. — BULLA. 



59 



BULLA.— Dipper or Bubble. 



Animal— a Limax: Shell nnivalvet convolute, unarmed 

 with teeth ; aperture a little straitened^ oblong, longitu- 

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



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

 instances so nearly allied to the latter, i. e. the Cypraea, 

 that much caution is necessary in order to prevent confu- 

 sion in the classification; for many of the Cypraeae, when 

 young, so nearly resemble some of the Bullae, that authors 

 have actually intermixed the genera. However, one 

 grand mark of distinction in this genus is, tliat, in what- 

 ever stage of growth its species are found, they never 



