37 



Key to Species. 

 I. Shell cylindrical. 



a. Rather coarse longitudinal .striation. Length 115, greatest diam. 15 mill, inagnijictcin. 

 a' . .Sculptured with about 80 threadlike riblets. Length 90, greatest diam. 10 mill, profiindorum. 



n. Shell decidedly compressed, nearly straight. 



a. Nearly elliptical in section Hunger f or di. 



a'. Trigonal in section Sibogae. 



42. Dentaltuni proftmdortim E. A. .Smith. PI. IV, figs 14 — 16. 



1S94. Dfiitalium profiiiidoniin Smith, Annals and Mag. N. H. (6), XIV, p. 167, pi. 4, fig. 18. 

 1897. Dentalhnii profundorum Smith. PiLSBRV & Sharp, Man. of Conch., vol. XVII, p. 79, 

 pi. 6, fig. 82. 



Stat. 88. o°34'.6N., 119° 8'.5 E. 1301 Metres. Fine grey mud. 4 Spec. 

 Stat. lot. 6° 15' N., I20°2i' E. 1270 Metres. Fine grey mud. i Spec. 



Diagnosis. .Shell large solid, moderately curved, sculptured with about 80 fine thread- 

 like plano-convex ribs, usually rather broader than the interstices; with numerous fine growth 

 striae making faint and regular impressions on the ribs. Colour dull buff, but sometimes brilliantly 

 white. Peristome subcircular, white inside, in some specimens very thickly edged, in others 

 rather thin. Length 90, greatest diam. 10 mill. 



Distribution. Off Colombo, Ceylon 6°32'N., 79°37'E. in 675 fms (Investigator). 



Remarks. The four specimens of Stat. 88 are e.xactly like those examined by Mr. E. 

 A. Smith. They are dull buff and much eroded showing many irregular patches where the 

 shell's outer layer has been broken away. Only one of these specimens has a slit measuring 

 nearly 5 mill. 



The specimen of Stat. loi is of a beautiful shining white and has a long narrow slit 

 measuring 14 mill.; the white colour is probably due to the local condition of the soil. The 

 same has been observed in D. candidiun Jeffreys, a species belonging also to the subgenus 

 Fissidentalium and distributed over the ea.stern and western Atlantic and the gulf of Mexico. 

 Dall remarks about that species : " Under favorable circumstances this species may be of a 

 most brilliant milk-white, but nearly all the specimens are dull ashy gray in color, even when 

 living and in perfect order. I suppose the white ones are those which happen to live in pure 

 sand, while the ordinary form comes from mud or ooze". 



*43. Deiitaliiiin inagnifiaim E. A. Smith. PI. II, figs 32, 32^". 



1896. Dcntaliiiin niagnificnin E. A. Smith, Ann. Mag. N. H. (6), XVIII, p. 371. 



1897. Dcntaliiiin magiiificinn E. A. Smith. Ph.sbkv & Sharp, Man. of Conch., vol. XVII. 



p. 78 and 251. 



1898. Dentalium viagnificuiii E. A. .Smith. Alcock & ANDERSON, Illustr. of the Zool. of the 



Investigator, Mollusca Pt. II, pi. VII— VIII. Calcutta. 

 1902. Dentalium niagnificnin E. A. Smith, figured in A. Alcock. A naturalist in Indian seas. 



