472 PROCEEDINGS OF THE ACADEMY OF [1897. 



This is one of those simple species of the subgenus Lcevidentalium 

 which has no prominent specific characters. It is still readily dis- 

 tinguishable from other smooth forms of the Miocene or Oligocene 

 of this region. D. pyrum is, perhaps, nearest, but that has a dis- 

 tinctly ovate or pear-shaped section. 



Dentalium pyrum n. sp. PI. XI, figs. 6, 7. 



Fragments, by which alone this species is known to us, indicate a 

 shell of slight curvature and slow increase ; thin ; distinctly ovate in 

 section, compressed laterally, the narrow end of the egg-form toward 

 the concave side. Surface smooth except for light growth-lines, 

 polished. Apex with a narrowly oblong orifice, passing into a short, 

 narrowly V-shaped notch on the convex side of the tube ; the orifice, 

 except at the slit, surrounded by an erect sheath. 



Length of largest fragment 6*45, greatest diam. at larger end 1*8, 

 least 1*65 mm. ; diam. at smaller end 1*3 x T4 mm. 



The apical characters are exactly as in the recent Antillean D. 

 perlongum and D. matara Dall. It is the typical Antalis apex. 



Dentalium precursor n. sp. PI. XI, figs. 12, 13, 14. 



Shell small, thin, slowly tapering, moderately arcuate, compressed 

 between the convex and concave side?, the section therefore oval. 

 Surface smooth except for very fine growth-lines, without longitudi- 

 nal sculpture. Dimensions of type, which is broken at both ends : 

 length 5*6, transverse or greatest diam. at larger end *95, least "85 

 mm. 



A member of our subgenus Compressidens, 6 but less rapidly in- 

 creasing in transverse diameter than the several recent American 

 species, among which it is most like Dall's D. ophiodon. We know 

 of no allied form in the American tertiaries. It is readily distin- 

 guished from other smooth forms described herein by the vertically 

 compressed and more arcuate tube. 



Cadulus phenax n. sp. PI. XI, figs. 23, 2i. 



Shell very slender, acicular, well curved posteriorly ; rather 

 abruptly swollen quite near the aperture, contracting rapidly an- 

 teriorly, gradually tapering posteriorly to a small apex ; nearly 

 circular in section ; surface smooth, glossy, with slight growth lines 

 but no corrugation or circular riblets posteriorly. Aperture circu- 

 lar, somewhat oblique ; apical orifice circular with entire edge. 



Length 6*5, greatest diameter 0*8 mm. 



6 Type D. pressum Sharp & Pilsbry. 



