INTRODUCTION. 1 1 



The following are the Worms of the Order 

 MoLLUSCA, which construct and inhabit calcareous 

 shells, the objects of our present consideration. 



Doris, or (according to Poli) Lophyrus ; Chiton. 

 Triton; Lepas, 



Ascidea ; Pholas, My a, Solen, Mytilus, 

 Tethys; Telli?ia, Cardium, Mactra, Donax, 

 Venus, Spondylus, Chama, Area, Ostrea, 

 Limax; Pinna, Conus, Cyprcea, Bullae Voluta, 

 Buccinum, Stromhus, Murex, Trochus, 

 Turbo, Helix, Nerita, Haliotis, Patella, 

 Terebella; Denialium, Serpula, Teredo, 

 Nereis 5 Salella, 



The animals inhabiting the Anomia and Nau- 

 tilus are either std generis, or have hitherto been 

 unsatisfactorily described. 



Before we proceed to the systematic arrange- 

 ment and explanation of the Genera, it will be 

 necessary to acquire some knowledge of Ter- 

 minology, as without this their technical de- 

 scriptions will be unintelligible. 



