138 SIPHONODENTALIUM. 



Group of S. teres. 

 S. TERES Jeffreys. PI. 26, fig. 72. 



Shell cylindrical, gradually tapering to the basal point or poste- 

 rior extremity, gently curved, thin, glossy, and semi transparent. 

 Sculpture, none except fine and numerous lines of growth; color 

 whitish ; mouth circular ; apex slightly but distinctly notched above 

 and below. Length 0'35, breadth 0'05 inch. (Jeffreys'). 



North Atlantic, (' Porcupine' Stations 16, 17, I7a). 



Siphodentalium teres JEFFR., P. Z. S., 1882, p. 661, pi. 49, f. 5. 



The position of the terminal notches in this species differs from 

 that of the slits in Dischides, being placed one on the convex and 

 the other on the concave end of the shell in S. teres, instead of being 

 bilateral as in that shell. (Jeffreys). 



Section PULSELLUM Stoliczka, 1868. 



Pulsellum STOL., Cret. Fauna of S. India, ii, p. 441, for S. lofo- 

 tense, affine and pentagonum=quinquangulare. FISCHER, Manuel 

 de Conchyl., p. 894. 



Siphonentalis G. O. SARS, Moll. Reg. Arct. Norv., p. 104 (1878), 

 for S. lofotensis, S. affinis and S. tetragona=quinquangulare. 



Siphonodentalis [sic] CLESSIN, in Systemat. Conchylien-Cabinet, 

 vi, Heft xi, 424te Lieferung, p. 30 (1896). 



Similar to Siphonodentalium except that the shell has no apical 

 slits and the foot-disk bears a terminal filament. Type S. lofotense 

 Sars. 



The name Pulsellum was proposed for the same three species upon 

 which Siphonentalis was founded a decade later. Meantime, Mon- 

 terosato had removed S. quinquangulare to his new genus Entalina, 

 leaving S. lofotense and affine to bear the earlier name. The addi- 

 tional species now placed here are of uncertain affinities; and the 

 posterior simplicity may in some cases be the result of loss of teeth 

 by breakage, which is frequent enough in Siphonodentaliidce with 

 lobed apices to pretty thoroughly vitiate any attempt to draw hard 

 and fast lines using the slits as a basis. 



S. LOFOTENSE M. Sars. PI. 24, figs. 40, 41, 42, 43, 44. 



Shell rather solid, white, but little pellucid, cylindrical, smooth ; 

 growth-striae somewhat oblique, moderately conspicuous ; form nar- 

 rowly subarcuate, moderately attenuated toward the apex. Aper- 



