A. £J. Verrill — Mollusca of the New England Coast. 217 



Dentalium occidentale, var. sulcatum, nov. 



Shell of moderate size, thin, translucent white tinged with very 

 pale yellowish or bluish, moderately curved, more decidedly behind 

 the middle, tapering regularly and rather rapidly from the anterior 

 to the very slender posterior end. The entire surface is covered by 

 well marked, nearly i-egular, narrow raised ribs with nearly perpen- 

 dicular sides and rounded summits, separated by well-defined, 

 strongly marked, concave grooves, which are about twice the width 

 of the ribs anteriorly, but posteriorly are of about the same width. 

 The ribs and furrows show on the interior of the shell within the 

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

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

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

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

 ture 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 

 anterior end, 3'"'" ; at the posterior end, •6""". Some specimens are 

 slightly more slender than the one measured. 



Station 2076, in 900 fathoms, one living S2Jeciraen ; station 2077, in 

 1255 fathoms, four living (No. 35,093), and station 2079, in 75 fath- 

 oms, one living specimen. 



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

 gitudinal sculijture, 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 lesembles some young specimens of the 

 typical jD. 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 evi- 

 dently intermediate between the two forms, in the character of the 

 sculpture and thickness of the shell. 



Dentalium, sp. g. 



Shell small, very slender, considerably curved. Surface covered 

 with very numerous, regular, microscopic, longitudinal lines, separated 

 by narrower striae. Anterior aperture circular, slightly oblique. 

 Posterior aperture very small, squarely truncated in one specimen, 

 oblique in the other, without any slit. 



