1905.] NATURAL SCIENCES OF PHILADELPHIA. 117 



layer usually projecting slightly, the margin shallowly notched at the 

 narrow end of the orifice, the notch slightly excentric on the convex 

 side of the shell (fig. 46). ^ • 



Length 41, diam. at aperture 3.6, at apex 1 mm. 



Length 29, diam. at aperture 3.1. at apex 1.2 mm. (immature shell). 



Heda, Izu, with D. coruscuyn. Type No. 88,319, A. N. S. P. 



This is probably nearer D. weinkauffi than to any other Japanese 

 species now known. It apparently belongs to the group comprising 

 D. entails, occidentale, etc., and referred to the subgenus Antalis, but 

 it is also about equally as much related to D. agassizi, a form from the 

 Panamic region in 322 to 1,020 fms. 



Dentalium (Laevidentalium) coruscum n. sp PI. V, figs. 42, 43. 



Shell well curved, thin-walled at the oral end, somewhat thickened 

 at the apex, circular in section throughout; the greatest diameter 

 contained 11 times in the length. White. The surface is polished, 

 very faintly marked with growth-lines on the larger half. The apical 

 orifice is shortly ovate, the narrow end toward the convex side of the 

 shell, where there is a slight wave of the margin. 



Length 33, diam. at apex 1, at aperture 3 mm. 



Heda, Izu, at entrance to port, in 167 fms. Type No. 88,320, 

 A. N. S. P. 



This form is related to D. leptosceles Watson, and luhricatum Sowb. 

 from Australia. My key to the species of Loevidentalium brings it to 

 the latter species except in the matter of size, luhricatum being about 

 double the dimensions of coruscum. This discrepancy, together with 

 the widely separated habitats of the two forms, indicates specific 

 diversity. 



The curvature, measured from a chord connecting the ends, to the 

 greatest convexity of the outer curve, is 4 mm., about one-eighth the 

 length of the shell. 



Dentalium (Rhabdus) cerinum n. sp. PI. V, figs. 40, i\. 



The shell is thin, almost straight, circular in section at the anal end, 

 barely perceptibly compressed from side to side at the oral end ; slender, 

 the greatest diameter contained about 17 times in the length; trans- 

 lucent whitish. The surface is glossy, sculptured with very fine rather 

 close and regular circular impressed lines and some coarser more widely 

 spaced impressions indicating periods of growth-arrest. 



Both apertures are simple, without slit or notch. 



Length 33, diam. at apex .9, at aperture 1.9 mm. 



Shimidzu, Suruga, off the spit. Type No. 88,305, A. N. S. P. 



