MUSEUM OF COMPAUATIVE ZOOLOGY. 425 



angularity especially in front until the shell is examined from behind " end 

 on," when it will be |)ercei)tible ; this form is struighter than the type. The 

 aperture is not at all obli([ue. There is a wide ratlier 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 mm. long, height of the 

 arch 3.5 mm., aperture 3.0 and anal end 0.0 mm. in diameter. The variety 

 obsciirum is 28. mm. long, aperture 2.0 and anal end 0.5 mm. in diameter. 



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

 coral, near Barbados, temperature 56°. 5. Also (the typical fornj) at U. S. Fi.sh 

 Commission Station 2145, in 25 fms., mud, near Aspinwall. Also in 12 fms., 

 twelve miles east from Fryingpan Shoals, South Carolina, Dr. W. H. Hush, 

 U. S. N. Also Barbados, ^c/e II. Cuming. 



This shell was confounded with D. hexagonum Gould, a large Chinese species 

 of similar form, by Sowerby and Reeve. The typical form of D. Gouldli is 

 longer, more slender, and less curved than the figures of Reeve and Sowerby, 

 which represent a young D. hexagonum. It is just possible that the supposed 

 variety may prove distinct, 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 ordi- 

 nary 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 teria-cotta. 



Dentalium ceras Watson. 



Dentalium ceras Watson, Linn. Soc. Journ., XIV. p. 510, April, 1879. Dall, Bull. 

 M. C. Z., IX. p. 37, 1881. Watson, Chall. Gastr., p. 3, pi. i. fig, 4, 1885. 



Habitat. Station 33, Gulf of Mexico, in 1568 fms. Station 193, off Mar- 

 tinique, in 169 fms., sand. Temperatures 40°.5 and 51°. Pacific Ocean, Chal- 

 lenger Expedition. 



By a lapsus in the text of the Bulletin one of Watson's specimens was stated 

 to come from the " Atlantic " west of Valparaiso, instead of the Pacific, as is 

 evident from the context. A comparison made by the kind assistance of Mr. 

 Watson confirms the identification of the Blake shell, which it thus seems is 

 really found in both oceans. It is close to D. capillosum, but is shorter, in- 

 creases more rapidly, and has a wider anterior end. The Blake specimens 

 were both dead, the Challenger specimen living, when taken. 



Dentalium capillosum Jeffreys. 



Dentalium capillosum Jeffreys, Ann. Mag. Nat. Hist., p. 153, Feb., 1877 ; P. Z. S. 1882, 

 p. 658, pi. xlix. fig. 1. 



Habitat. Whole North Atlantic, Challenger, Valorous, and Travailleur 

 Expeditions. Off Havana, Sigsbee, in 119 fms. Station 193, off Martinique, 



