188 M. Deshayes' Monograjjh of Dentalium. 



Length 1 inch 2 Hnes. Diameter of the base rather more than 1 

 line. 



23. D. INCERTUM, Desh. D. testd tereti, angustd, subarcuatd, apice 

 acutissimd, lesvigatd, nitidd. 



D. nitens ? Sowerhy, Min. Conch, pi. 70, f. 1, 2. 

 Foss. in GalUa. 



Resembles in form the D. pseudo-entalis, but is without its striae, being- 

 smooth like D. Entails, but much narrower, more curved, and pointed. 

 From the preceding species, of which it may eventually prove to be only 

 a variety, it differs in its greater curvature, its larger size, its more acute 

 apex, and the greater thickness of its shell. 



Length 1 inch 6 lines. Diameter of the base 1^ line. 



24. D. RUBESCENS, Desh. D. testd tereti, subarcuatd, translucidd, 

 rubescente, Icevigatd, acuminata ; extremitate intus sulco dorsali. 

 Habitat in mari Mediterraneo ? 



Intermediate between this and the succeeding section in which the 

 species are cleft at the posterior extremity of the shell ; but in this the shell 

 is only marked on the interior by a short median dorsal groove, which does 

 not penetrate through to the external surface. Colour red. Shell trans- 

 parent, very smooth and very shining ; curvature not considerable ; open- 

 ing rounded, rather oblique, with very sharp margins. There is no ap- 

 pearance of strise, whether longitudinal or transverse. 



Length 1 inch 2 lines. Diameter of the base 1^ line. 



25. D. DUPLEX, Def. D. testd tereti, angustissimd, subcylindricd, 

 extremitate duplicatd. 



Foss. in Gallia. 



Shell very narrow, acicular, subcylindrical, generally truncated at the 

 apex, from the opening of which constantly projects a short tube, much 

 smaller in diameter, and appearing to issue from the larger one ; entirely 

 •smooth, little curved, and diminishing very shghtly from the base to the 

 apex. 



Length 9 lines. Diameter of the base | a line. 



