MANUAL. 



THE animals which furnish the testaceous 

 subjects about to be described, are a portion 

 of that multitudinous division which have a 

 soft body, without vertebral column, and which 

 are not supported by a bony nor a cartilaginous 

 skeleton. In general their shells are external, 

 wholly or partially concealing and protecting 

 the body ; but in some few instances they 

 are themselves internal, and enveloped by the 

 body. 



They may be divided into two great families. 



