DENTALIUM-ANTALIS. 49 



aperture, in reverse, the whole thickness of the shell conforming to 

 the sculpture as if they were corrugations of its substance. The oval 

 aperture is relatively large and circular, very little oblique, and 

 usually with the very thin edge more or less broken. Posterior 

 aperture very small, usually plain and without any notches, but in 

 one of the most perfect specimens it has a slight lateral notch on each 

 side ; in others there is a small dorsal notch. 



Length of one of the largest specimens 20, diameter at the ante- 

 rior end 3, at the posterior end 0'6 mill. Some specimens are 

 slightly more slender than the one measured. (Verrill). 



South of A/ova Scotia, east of Cape Cod, lat. 41 9' 40" to 41 IS', 

 long. 66 2' 20" to 66 50', at the following Stations : 2076, in 906 

 fathoms, one living specimen; station 2077, in 1255 -fathoms, four 

 living, and station 2079 in 75 fathoms, one living specimen (U. S. 

 Fish Commission). 



D. occidentale var. sulcatum VERRILL, Trans. Conn. Acad., vi, p. 

 217 (June, 1884). 



This variety resembles D. candidum Jeffreys in its form and lon- 

 gituflinal sculpture, but lacks the transverse lines between the ribs ; 

 the posterior end is also more slender and more curved than shown 

 in his figure. It also closely resembles some young specimens of the 

 typical D. occidentale but the latter has not so strongly marked and 

 regular ribs and grooves, nor does the sculpture extend entirely 

 through the thickness of the shell so as to appear on the inside, as 

 in the present form. Specimens often occur, however, that are 

 evidently intermediate between the two forms, in the character of 

 the sculpture and thickness of the shell. ( Verrill). 



We have not seen this form. 



D. ^NIGMATICUM Jordan. PI. 9, figs. 58, 59. 



Shell subcylindrical, very slender, thin, slightly curved, lusterless, 

 and opaque. Sculpture, 26-28 longitudinal ribs, which are thin, 

 almost sharp, and traverse the entire length of the shell. No lon- 

 gitudinal microscopical striae are visible between these ribs, merely 

 the usual transverse lines of growth. Color, creamy-white, margin 

 at the anterior end jagged, as is usual in other species of this genus. 

 No notch or slit is visible at the posterior end, which, however, 

 appears when examined by a strong lens to be slightly broken. 

 Length 25, diam. 2 mill. (Jordan}. 



Faroe Channel, if cold area," 640 fms. ; off west coast of Ireland, in 

 1000 fms. 

 4 



