1911.] 



NATURAL SCIENCES OF PHILADELPHIA. 



167 



actually flattened on the sides. The shell-wall along the, concave 

 side is decidedly thicker than that opposite along the convex side. 



Another Episiphon, of very slender form, thin shell and circular 

 section, occurs in the Santo Domingo Oligocene beds. As the material 

 is not very abundant, only one being presumably adult, the species 

 was omitted from my account of the Scaphopods of that deposit. 

 The largest specimen seen has a length of 13 mm. and a greatest 

 diameter of 0.9 mm., and is almost smooth. 



Dentalium (Episiphon) schumoi n. sp. Fig. 5. 



Shell small, slightly curved, excessively slender, the adults but 

 slightly tapering, young shells acicular; rather thin; surface finely 

 striated circularly, becoming on the posterior half strongly annulated 

 by rather regularly spaced, close grooves, slightly oblique, and cutting 

 the surface into narrow segments much as in D. (Fustiaria) circinatum. 

 Tube strongly compressed laterally throughout; apex simple or with a 

 short projecting pipe or tube. 



Length 8.2, antero-posterior diameter at aperture 0.78, at apex 0.56 

 mm.; lateral diam. at aperture 0.6, at apex 0.46 mm. The specimen 

 has evidently lost in length by breakage. 



Bowden bed, not uncommon. 



O 



m 



Fig. 5. — Dentalium schumoi, specimens of various ages. 



