EAST AMERICAN SGAPHOPOD MOLLUSKS. 



39 



over the entire shell. All sculptural features are confined to the outer 

 shell layer and are more or less obliterated in most specimens. 



The type, Cat. No. 50191 (a), U.S.N.M., was dredged at the U. S. 

 B. F. Station 2513 between Halifax and Le Havre Bank, in 134 

 fathoms, bottom of gray ooze; temperature, 43.6° F. It measures- 

 length, 62 mm.; diameter, 4.75 mm.; arc, 3.5. 



Eight lots hi the museum collection are all from off Nova Scotia 

 in from 57 to 134 fathoms, with bottom temperatures rangmg from 

 36° to 44° F. One of these measures — length, 88 mm. ; diameter, mm. ; 

 arc, 5. 



The tendency to abnormality m curvature and to other accidents 

 of sha])e is very remarkable, so much so that a really normal shell is 

 hard to select. Variance hi the degree of curvature is unusual hi the 

 Dentalia — a fact which emphasizes this exception. 



The absolute identity of this subspecies with Sars's typical Den- 

 talium agile and Jeffreys's D. ahyssorum of European waters will 

 likely remain a question of individual opinion. The differences 

 between these west and east Atlantic shells are much the same as 

 those noted under D. entale stimjjsoiii (p. 35). When viewed in 

 quantity there is no doubt of a difference. Selected specimens will 

 reestablish an identity. In general the American shells, despite a 

 softer and more chalky texture, possess a sharper sculpture, and the 

 notable tendency to abnormality in shape and curvature is absent 

 from east Atlantic forms. Doctor Dall's D. agile oleacinum of the 

 Pliocene is a smooth sculptureless shell and not synonymous with 

 B. agile subagile. Doctor Watson's D. e. ortJirum is an east Atlantic 

 8ubs])ecies, to which he referred specimens taken by the Challenger 

 off Prhice Edward Islands, m 140 fathoms. I have no doubt but that 

 these shells'should be referred to our D. a. subagile. 



The following are the United States National Museum records : 



Num- 

 ber of 

 speci- 

 mens. 



Cat. No. 

 r^S.N.M. 



50191a 



50191 



50188 



50189 



50192 



52302 



5019.3 

 314325 



Locality. 



Between Halifax and Le Havre Banks, U. S. B 



F. Station 2513 



Between Halifax and Le Havre Banks, U. S. B 



F. Station 2513 



Between Middle Ground and Halifax, U. S. B. F 



Station 2505 



Between Middle Groundand Halifax, U. S. B. F 



Station 2506 



Between Halifax and Le Havre Banks, U. S. B 



F. Station 2514 



Between Halifax and Le Havre Banks, U. S. B 



F. Station 2512 



Le Havre Bank, U. S. B. F. Station 2515 



75 miles east Cape Sable, Nova Scotia, (F. W 



Clapp, collector) 



I Type. 



Remarks 



134 fms., 44° gy. oz. 



134 fms., 44" gy. oz. 



93 fms., 42°, dk. br. m. 



127 fms., 43°, dk. br. m. 



126 fms., 43°, bk. m. 



103 fms., 43°, br. m. 

 57 fms., 36°, s. g. 



105 fms., m. (O. Bryant). 



