PREFACE. 



indebted, according to the judgement of a 

 large majority, for the most perspicuous 

 arrangement of testaceous animals which 

 has hitherto been offered to the pubHc. 

 His system has been followed in the pre- 

 sent treatise, not because it is considered 

 faultless, or incapable of great improvement, 

 but because, upon the whole, it is more sim- 

 ple and inteUigible, and less likely to deter 

 beginners, than any other with which we 

 are acquainted. At the same time it would 

 be blameable servihty to adhere to the 

 very letter of the Linnaean law ; — some 

 of the terms are decidedly objectionable, 

 and are therefore totally discarded ; some 

 few subdivisions of genera are added, 

 which, perhaps, may seem nearly to pre- 

 clude the necessity of forming new ge- 



