BULLA-D/PP^A 73 



Genus. -BULLA.* PJwraJ, w/te. 



DIPPER OR WATER BUBBLE. 



Generic Character.^ Shell univalve, invo- 

 luted, often without any spire, smooth ; J shape 

 suboval, inflated ; aperture longitudinal, general- 

 ly the length of the shell, entire at the base ; 

 columella oblique, smooth. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



This genus is perhaps less accurately defined 

 than any other of the Linnsean genera : it con- 

 tains an assemblage of shells presenting a very 

 varied appearance, indeed it seems as if it had 

 been formed to be a receptacle for including all 

 the species that could not find a place elsewhere. 

 The most distinguishing characteristic of the 

 Bulla is its gibbous or inflated figure, to which it 

 owes its name, signifying water bubble. One 



* Plate II. fig. 6, 8, 9. 



*f* It is hoped that Teachers who use these lessons will re- 

 collect that it is most important when the children are drawing 

 out the generic character, to bring before them a great variety 

 of shells, that they may group them according to resemblances 

 which they perceive, and under direction learn by observation, 

 their distinctive characters. 



J The Bullae are said to be smooth because their surface 

 has never any projections. 



