34 BULLETIN ■ 111, UNITED STATES NATIONAL MUSEUM. 



246, off Grenada, in 154 fathoms, ooze, bottom temperature 56°. 

 It was also dredged in Barbados by the State University of Iowa 

 Expedition in about 100 fathoms. 



The transverse sculpture imparting a rough file-like surface to the 

 shell is a feature at once separating this large species from any other 

 of the region under consideration. It appears to belong to the con- 

 tinental slope zone, and is at present only known from the Lesser 

 Antilles and the Bahamas in temperatures ranging from 47.5° to 

 58° F. 



Subgenus ANTALIS H. and A. Adams, 1854. 



1854. Antalis H. and A. Adams, Gen. Rec. Moll., vol. 1, p. 457 (1854).' Type, 

 D. entails Linnaeus. 



Tip prismatic or round, with primary riblets ranging from 6 to 18, 

 which are less strongly developed and prominent than in Dentalium 

 s. s. and generally disappear entirely in the senescent stages of the 

 shell if not earHer. The apical characters consist of a notch on the 

 convex side or may be lacking. Transverse sculpture is variable or 

 absent. 



As already noted the differences between this and the preceding 

 subgenus are not very sharply drawn. It seems to have been made 

 the receptacle for various forms of Dentalia that do not readily fil 

 elsewhere, hence the group is a somewhat heterogeneous one. TIk^ 

 American species referred here are all less strongly ribbed than are 

 those included under Dentalium s. s. The American species conven - 

 iently group as follows: 



SYNOPSIS OF THE GROUPS OF ANTALIS. 



Primary ribs 16-18, more or less distinct; senile stage sculptureless. Northern dis- 

 tribution group of Dentalium ocddeyitale, page 34. 



Primary ribs 16-18, well defined; senile stage sculptureless, glazed. Southern dis- 

 tribution group of D. bartletti, page 54. 



Primary ribs 9-14, fine; color pattern absent; senile stage polished; intercostal 

 sculpture present group of D. ceratum, page 49. 



Primary ribs 9, coarse; color pattern present; senile stage not polished; intercostal 

 sculpture present group of D. antillarum, page 43. 



Primary ribs 6, their distribution unsymmetric group of D. disparile, page 47. 



KEY TO THE GROUP OF DENTALIUM OCCIDENTALE. 



Distinctly sculptiired. 



Long and slender (over 40 mm.) Dentalium agile subagile, page 38. 



Not long and slender (under 40 mm.). 



Sculptural features confined to outer superficial shell layer. 



D. occidentale, page 40. 

 Sculptural features not confined to outer superficial shell layer. 



D. occidentale georgiensis, page 43. 

 Not distinctly sculptured D. entalis stimpsoni, page 35. 



I For discussion of the extensive synonymy of Antalis see Pilsbry and Sharp, in Tryon's Manual of Con- 

 chology, vol. 17, pp. 37 and 38. 



