EAST AMERICAN SCAPHOPOD MOLLUSKS. 



41 



Length, 34 mm.; diameter, 3.75 mm.; arc, 2 (almost complete shell). 



Length, 34 mm.; diameter, 4 mm.; arc, 1.75 (part of tip lost). 



The type has not been preserved. 



This is a cold-water species, closely related to Dentalium entale, D. 

 agile, D. ahyssorwm, and their subspecies. It ranges from New- 

 foundland to off Hatteras, generally on the continental slope, well 

 offshore, in depths from 20 to 1,000 fathoms. It is not usually found 

 together or associated with D. entale stimpsoiii, from which it differs 

 by its sculpture, its more slender form, and by its even increase in 

 diameter. From D. a. suhagile it differs chiefly in the smaller size 

 and in its regular curvature. 



Two subspecies may be recognized. 



DENTALIUM (ANTALIS) GCCIDENTALE OCCIDENTALE Stimpson. 



Plate 4, figs. 1, 5, 6, 7, 9. 



This subspecies includes all the specimens answering the general de- 

 scription just given under D. occidentale except the group of thinner, 

 more prominently sculptured forms, which will be considered in the 

 next following heading as a distinct subspecies. This typical sub- 

 species is characterized by the thin outer shell layer, or periostricum, 

 overlying the midlayer of softer chalky nature and the resultant 

 decrease in the definiteness of all its sculptural features. It is the 

 usual common form of the species. 



Measurements and depth range and geographic distribution are the 

 same as for D. occidentale . 



The following: lots are in the museum collection: 



