DENTALIUM. 29 



D. cooKEi Sharp & Pilsbry, n. n. Unfigured. 



Shell thin, very narrow, acuminate, polished, subpellucid, little 

 arcuate; fluted with about 14 ribs, which are not equidistant, only 

 slightly elevated, but distinctly defined at their bases; ribs at the 

 apex coalescent and vanishing ; interstices shallow and polished. 

 Length V2b, diam. at base 0*0625 inch. (Cooke). 



Gulf of Suez (MacAndrew). 



D. acus Cooke, Ann. Mag. N. H. (5), xvi, p. 274 (Oct., 1885). 

 Not D. acus Eichwald, 1856. 



Probably a young shell, but very distinct from any known species. 

 It is a most graceful shell, exquisitively marked and polished. One 

 specimen. (Cooke). 



D. usiTATUM E. A. Smith. PL 10, figs. 68, 69. 



Shell small, moderately slender, white, little arcuate; having 

 about 20-25 very delicate, equal longitudinal lirte, sculptured with 

 oblique lines of growth. Scarcely slit at the apex. Length 31, 

 greatest diam. 2'7 mill. (Smith). 



Off Colombo, Ceylon, lat. 6° 32' N., long. 79° ST E. in 675 fms. ; 

 Bay of Bengal in 597 fms. (Investigator). 



D. usitatum Smith, Ann. and Mag. N. H. (6), xiv, p. 168, pi. 4, 

 f. 16, 16a (Sept., 1894). 



The two specimens examined do not look as if they were young 

 shells. The white color is varied here and there with narrovv, 

 oblique, somewhat pellucid zones. (Smith). 



Group of D. carduus. 



Shell longitudinally ribbed, latticed by circular riblets or fine 

 raised lamellae, often rising into minute knots or spines at the inter- 

 sections. 



The species following would apparently fall into Sacco's subgenus 

 Coccodentalium (Boll. Mus. Zool. ed Anat. Comp. R. Univ. di Tor- 

 ino, xi, 1896, p. 98). We have not seen D. radula Schroter, Gmel., 

 the type of that group, and Sacco gives no diagnosis, but the descrip- 

 tion of that Pliocene species indicates sculpture like carduus. Other 

 members of the same section are D. tryoni Pils. & Sharp of the 

 Miocene of San Domingo, and possibly the recent D. cancellatum 

 Sowb. 



