INTRODUCTION. 



CHAPTER I. 



CLASSIFICATION. 



DEFINITION OF THE TERM " CONCHOLOGY." CONFORMITY OF 

 SHELLS WITH THEIR INHABITANTS. CEPHALIC MOLLTJSKS OR 

 UNIVALVES. ACEPHALA OR BIVALVES. TUNICATA. SPE- 

 CIES. VARIETIES. MONSTROSITIES. REVERSED SHELLS. 

 SYNONYMY. NOMENCLATURE. 



Definition of the term " Conchology." Conchology *, 

 as a branch of Natural History, treats of the Mollusca 

 or that great division of invertebrate animals which have 

 soft bodies and an organization superior to that of 

 insects and only inferior to that of fishes. It properly 

 comprises the study, not only of the shell or outer cover- 

 ing of the mollusk, but also of the whole animal, al- 

 though it has sometimes been used in a more limited 

 sense, in contradistinction to the term "malacology," 

 which has exclusive reference to the soft parts of the 

 animal. Linne" included the Mollusca in his great class 

 Vermes some of them as Vermes Mollusca and others 

 as Vermes Testacea ; but as the first of these divisions 

 comprised a very heterogeneous assemblage of inver- 

 tebrate animals, and as the testaceous Annelids were 

 united with the latter, the classification proposed by liim 



* Compounded of two Greek words, Koyx??,"a shellfish, and Aoyos, 

 a treatise. 



