468 PROCEEDINGS OF THE ACADEMY OF [1897. 



simile, in his paper "On the Topography and Geology of Santo 

 Domingo," p. 244. It is named in honor of Maurice Cossmann of 

 Paris, whose fruitful labors upon the Parisian Eocene are justly 

 esteemed by workers upon Tertiary mollusks. 



Dentalium callioglyptum n. sp. PL X, figs. 10, 12 ; PI. XT, fig. 21. 



Shell large, solid and but very slightly curved ; noticeably com- 

 pressed between the convex and concave surfaces; decidedly taper- 

 ing. Sculpture, many longitudinal cords or riblets alternating with 

 threads, altogether numbering about 65 near aperture, about 40 

 near the middle of the length, the ridges averaging about the width 

 of the grooves ; the whole crossed by circular raised lamella? running 

 a little obliquely around the tube ; these lamella? very close, nearly 

 regular, most conspicuous in the intervals, and so fine that they are 

 scarcely visible to the unaided eye. The circular lamella? subobso- 

 lete toward the aperture in large specimens. Aperture slightly 

 oblique, judging by the lines of growth ; apex unknown ; but accord- 

 ing to the fragments before us both orifices are slightly oval in con- 

 sequence of the compression of the tube. 



Length unknown, but from the taper of the fragments probably 

 about 115 mm. ; greatest diam. of larger end of largest fragment 13, 

 least diam. of same 12 mm., length 15 mm. 



Another fragment from near the middle of the shell measures, 

 length 30, greatest diam. of larger end I'd, of smaller end 4 - 6 mm. ; 

 therefore tapering to the extent of 3 - 3 mm. in a length of 30 mm. 



The specimens were collected by Gabb, who referred them with a 

 " ? " to his D. affine. 



We at first thought to identify it with the recent D. cardials 

 Dal, which has similar file-like circular sculpture; but upon appeal- 

 ing to our kind friend at Washington for a comparison, the follow- 

 ing differential features became apparent: " D. cardmis is lighter ; 

 the fossil form is not so much curved and the elevated lines are dis- 

 tant, with no longitudinal sculpture between them ; the anterior part 

 of the adult carduus has fine longitudinal striae covering the inter- 

 spaces as well as the elevated riblets." 



D. Tryoni differs from this species in the character of the circular 

 stria? and some other features mentioned below. 



Dentalium Tryoni n. sp. PI. X, figs. 5, 9 ; PI. XI, fig. 22. 



Shell long, rather slender, slowly tapering and nearly straight, 

 the very slight curvature mainly posterior ; circular in section ; 



