12 iNTEODtJCTION. 



Gastropoda, and Scaphopoda, published in two parts by tlie Museum 

 of Comparative Zoology, under the direction of Prof. Alexander Ag- 

 assiz. The generosity of Professor Agassiz in permitting the use of 

 plates prepared for that report was decisive in insuring the prepa- 

 ration of this list. Other plates are made up of figures which have 

 appeared in the annual reports of the U. S. Commissioner of Fish and 

 Fisheries ; in the Proceedings of the National Mnseura ; the edition of 

 Gould's Invertebrata of Massachusetts, edited by Mr. W. G, Binney ; 

 Professor Verrill's and Miss Bush's papers in the Transactions of the 

 Connecticut Academy of Sciences; and the publications of the British 

 Museum. For the use of these cnts we are indebted chiefly to the 

 Smithsonian Institution and the U. S. Commissioner of Fisheries, Col. 

 Marshall Macdonald. 



In including or omitting gronps of moUusks in this catalogue the com- 

 piler has necessarily been guided by convenience rather than syste- 

 matic completeness. Some groups, such as the jSTudibranchiata, are so 

 imperfectly known from the region south of New England that it be- 

 comes imperative that they should be entirely omitted. An attempt to 

 include them would certainly have been more' likely to retard than to 

 advance the progress of science. For the same reason partly, and partly 

 because it is impracticable to reproJuce the figures, the entire group 

 of Cephalopoda, except the Argonaut and Spirula, has been left out. 

 Those who desire to study these difficult animals are referred to Pro- 

 fessor Yerrill's excellent reports upon the subject in the Bulletin of the 

 Museum of Comparative Zoology and the Transactions of the Connecti- 

 cut Academy of Sciences. The two exceptions are included merely be- 

 cause of one we have an excellent figure, and the shell of the other is 

 frequently obtained by collectors on our southern shores. 



Among those animals which frequent the sea-shore and are often - 

 found in as well as near the water, though really air-breathers, the 

 Auriculidcej Siphonariidce, and Gadiniidce can almost be regarded as 

 marine. Having good figures of some of tbem and desiring to err, if at 

 all, on the side of convenience to the amateur collector or beginner in 

 conchology, they have heen included in our list. For the same reason 

 Neritina, Cyreim, etc., have been inserted even when not strictly salt- 

 water species. 



The Pteropods, of the sea off our coasts, are rarely found by collec- 

 tors, and the nomenclature is not in a satisfactory state. Still it was 

 thought best to include a list of the species taken, with some additions, 

 chiefly from Professor Verrill's papers, though completeness or entire 

 accuracy is not claimed for it. The Heteropods, except Atlanta Cari- 

 naria and Oxygynis, are not included. 



It will be seen from these explanations that the present catalogue is 

 a working list for the benefit of collectors and students, rathisr than a 

 scientific treatise or thoroughly revised enumeration of the mollusk 

 fauna. Indeed it is in its quality of a stepping-stone to the latter that 



