A MONOGRAPH OF THE EAST AMERICAN SCAPHOPOD 



MOLLUSKS. 



By John B. Henderson, 



Of Washington, District of Columbia. 



INTRODUCTION. 



Diirinjj: the latter part of the eighteenth and the first quarter of 

 the nineteenth century many species of the ahundant shallow water 

 mollusks of the western Atlantic, especially of the larger and more 

 conspicuous Antillean forms, were described by European naturalists. 

 Between 1820 and 1840 several American naturalists, notably Conrad 

 and vSay, added a number of species to the American list, their 

 material coming mostly from the Atlantic and Gidf coasts of the 

 United States. At that time there had been little or no dredging 

 done, nor, indeed, had any attempt been made at systematic, nmch 

 less intensive, collecting. Only those easily accpiired mollusks were 

 known that lived either in the shallow water of bays or that had been 

 cast upon exposed beaches. As the American Scaphopods lire 

 below tidal range and are rarely found upon beaches they almost 

 wholly esca])ed the notice of the earlier collectors. A few Dentalia, 

 probably from Antillean beaches, had, however, found place in 

 foreign collections and were described in the careless manner of the 

 time, usually with doubtfid or no locality records attached. Such 

 species were Dentalium serrdstriatum of Tiirton, published in 1819 

 as coming from Dublin Bay, and also D. nehulosum of Deshayes in 

 1825. In 1834 Guilding described D. semisiriolatum and D. sowerhyi 

 as positively Antillean species, and these stand as the first recorded 

 of our Dentalia that may be accepted 'with reasonable assurance. 

 Chenu, in the first volume of his imposing series of Illustrations 

 Conchyliologiques, appearing jibout 1843, gives excellent figures of 

 his own and of Deshayes's species of Dentalium, some of which may 

 belong to the western Atlantic. These are Dentalium nehulosum 

 Deshayes (already referred to), D. translucidum Chenu, J9. nmericanum 

 Chenu, D. pictei (Deshayes) Chenu, D. ensiforme Chenu, and a few 

 others that are suspiciously like some well-known West Indian forms. 

 There are good reasons, to be later discussed, for rejecting them all 

 for our present list. 



