DENTALIUM. 21 



angles, and which obscure the angularity especially in front until 

 the shell is examined from behind "end on " when it will be per- 

 ceptible ; this form is straighter than the type. The aperture is not 

 at all oblique. There is a wide rather short notch, perhaps due to 

 erosion, at the convex side of the anal orifice in the shell figured. 

 Typical form shows no notch when perfect, and measures 30*0 mill, 

 long, height of the arch 3'5 mill., aperture 3*0 and anal end 0'6 

 mill, in diameter. The variety obscurum is 28'0 mill, long, aperture 

 2'0 and anal end 0'5 mill, in diameter. (Dall). 



Off Havana, in 127 fms. Variety at Station 299, in 140 fms. coral, 

 near Barbados. Also (the typical form) at U. S. Fish Commission 

 Station 2145, in 25 fms., mud, near Aspinwall; Galveston and Corpus 

 Christi, Texas (Singley). Also in 12 fms., twelve miles east from 

 Frying pan shoals, South Carolina, (Dr. W. H. Rush, U. S. N.). 

 Also Barbados (fide H. Cuming), East from Rio Janeiro, 59 fms. 

 (Albatross). Eocene of Trinidad (Guppy & Dall). 



D. gouldii DALL, Blake Rep., Bull. M. C. Z., xviii,p. 424, pi. 26, 

 f. 4 (1889) ; Bull. U. S. Nat. Mus., no. 37, p. 76, pi. 26, f. 4 ; Proc. 

 U. S. Nat. Mus., xii, 1889, p. 295 (1890). GUPPY & DALL, Proc. 

 U. S. N. Mus., xix, p. 325 (1896). D. sexangulare HILGARD & 

 HOPKINS, Rep. Borings Miss. R. and L. Borgue, Engineers Dept. 

 U. S. A., p. 48, pi. 3, f. 7 (1878), name preoc. D. texasianum 

 PHIL, and ? D. americanum CHENU, see below. 



The shell was confounded with D. hexagonum Gould, a large 

 Chinese species of similar form, by Sowerby and Reeve. The typical 

 form of D. gouldii is longer, more slender, and less curved than the 

 figures of Reeve and Sowerby, which represent a young D. hexago- 

 num. It is just possible that the supposed variety may prove dis- 

 tinct, in which case it may be called D. obscurum; but I inclined 

 at present to believe it to be nothing more than a variety. The 

 ordinary form is what has been called hexagonum by West Indian 

 collectors for many years, but the rounding off of the angles as the 

 shell becomes adult is not paralleled in the Chinese species, which 

 is much larger, and has a reddish dull surface, like pale terra-cotta. 

 (Dall). 



It is probable that this species was described three times before 

 the publication of Dall's description, but some doubt attaches to the 

 identity in each case. We therefore retain the name gouldii. 



The following is probably a young specimen of D. gouldii Dall, 

 which is known to occur at Galvestou. 



