134 ENTALINA. 



Rebecca Shoal, lat. 24° 02', long. 82° SI' 30" in 430 fms. (Wm. H. 

 Rush). 



SipJiodentalium platamodes Wats., Journ. Linn. Soc. Lond., xiv, 

 p. 519 (1879) ; Chall. Rep. Scaph. and Gastr., p. 13, pi. 2, f. 4.— 

 Dentalium platamodes Dall, Bull. U. S. Nat. Mus., no. 37, p. 76 

 (1889). 



I have hesitated a good deal in separating this from Sipliodental- 

 ium tetragonum liroc.=^quinquangulare E. For., with which it 

 agrees more closely than with SipJiodentalium pentagonum Sars. 

 Here, however, the longitudinal ribs are much closer, as well as 

 much more obsolete ; the shell is more curved throughout its whole 

 length, is more attenuated, and retains its square form and sharp 

 angles instead of becoming rounded as in S. tetragonum Brocchi. 

 Amidst all the variations of that very variable form I have not seen 

 any that connect it with this species ( Watson). It may be added 

 that the specimens dredged by Dr. Rush confirm the distinctions 

 between this species and the preceding. 



E. mirifica (Smith). PL 20, fig. 29. 



Shell small, strongly curved and acuminate toward the apex, 

 quadrate tubular, wider along the inner curve than along the outer ; 

 longitudinally delicately striate, very delicately sculptured with 

 growth-lines ; subconcave between the angles. Length 19, greatest 

 diam. 2? mill. (Smith). 



Off Trincomalee, Ceylon, 200-350 fms. 



Dentalium mirijicxiyn E. A. Smith, Ann. Mag. Nat. Hist. (6), xvi, 

 p.9, pl.2,f 1 (July, 1895). 



This little species is remarkable for the sharply curved end and 

 the subquadrate form. The four angles are acute at the tip, but 

 gradually become obtuse as the shell increases. The incurved side 

 is the broadest of all, and up the middle of it, especially towards the 

 apex, there is a raised striation more conspicuous than the rest. 

 This is so prominent at the end that, when viewed with the opening 

 towards the eye, five angles are visible. The two angles on the ex- 

 curved side, which is the narrowest of all, become almost obsolete 

 near the aperture. The form of the aperture, owing to the greater 

 width and flatness of the incurved side, is very like the letter D. 



Sipliodentalium quinquangulare Forbes is a much more slender 

 species, and more circular in section near the aperture. 



