EAST AMERICAN SCAPHOPOD MOLLUSKS. 53 



DENTALIUM (ANTALIS) TAPHRIUM Dall. 



Plate 7, fig. 8. 



1889. Dentalium taphriuvi Dall, Bull. Mus. Comp. Zool., vol. 18, p. 422. 



1889. Dentalium taphriuvi Dall, Bull. 37, U. S. Nat. Mus., p. 7(5. 



1897. Dentalium. taphrium, Pilsbry and Sharp, Tryon's Man. Oonch , vol 17, 



p. 58. 

 1901 (?). Dentalium taphrium Dall and Simpson, U. S. Fish. Comm. Bull, for 



1900, vol. 1, p. 455, pi. 54, fig. 19. 

 1903. Dentalium taphrium. Dall, Bull. 37, U. S. Nat. Mus., p. 76. 



The shell is rather short, awl-shaped, with its maximum curvature 

 at the base of the tip; thereafter it is but slightly curved. It quickly 

 expands in diameter at the start and thence through the middle and 

 anterior portions very gradually. A very constant and character- 

 istic feature is its apple green color. On the sculptured portion of 

 the shell are series of irregular zones of translucency encircling the 

 shell and so disposed as to impart a watered silk appearance. This 

 color feature, however, does not extend to the smooth anterior 

 portion of the cylinder, which is of a clear translucent apple green 

 color and is polished and shining. There are 14 sharp, well-defined 

 riblets, though originally probably nine primaries, which are quickly 

 increased to double or even more by subsequent intercalation; all 

 the riblets become lower and more square in outline, and finally 

 growing fainter disappear into a smooth, highly polished glassy 

 round cylinder. In the intercostal spaces is a network of micro- 

 scopic transverse and longitudinal lines, which also disappear on the 

 smooth, anterior portion of the shell. The longitudinal miscroscopic 

 lines are usually indistinct. There is a shallow apical notch on the 

 convex side. 



Length, 17 mm.; diameter, 2 mm.; arc. 75 (type). 



Length, 25 mm.; diameter, 2.25 mm.; arc, 2.1 (tip gone), Florida. 



The type. Cat. No. 95320, U.S.N.M., was dredged between Missis- 

 sippi Delta and Cedar Kojs in 30 fathoms, gray sand and broken 

 coral, being U, S. B. F. Station 2405; no bottom temperature given. 



There are also lots from off Cape Hatteras and Cape Lookout in 

 22 to 52 fathoms, and many from the Florida Keys region in 20 to 

 60 fathoms, the majority of the records coming from 30 to 45 fathoms, 

 just inside the Gulf Stream; also from Cabanas Harbor, Cuba, in 25 

 fathoms (form). 



In the many lots of specimens studied there are none that prolong 

 the final shell stage of smooth, glassy surface to the extent often 

 seen in Dentalium ceratum. The proportion of the smooth to the 

 sculptured portion in this species is usually about as one to seven. 



The differences between this and its nearest relative, D. ceratum, 

 are in the greater number of riblets; the green instead of yellow 

 color, and in the presence of translucent zigazg zones, wholly lacking 



