432 BULLETIN OF THE 



Cadulus acus n. s. 



Plate XXVII. Fig. 11. 



Shell small, very slender, slightly curved, variegated with translucent and 

 opaque white rings and encircling bands which become broader toward the 

 anterior extreme ; aperture circular, slightly oblique, the shell behind it rapidly 

 increasing to its point of maximum diameter, from which it very gradually 

 tapers toward the almost acute posterior extremity. Surface smooth, with 

 extremely fine circular grooves or lines, which, under a strong magnifier, are 

 visible over most of the posterior third of the shell with their interspaces, 

 recalling the rings of Ccecum trachea on a much more minute scale ; the rings 

 of opaque color sometimes coincide with the sculpture, but not constantly. 

 Lon. of shell, 8.0; diameter of aperture, 0.5 ; max. diam., 0.75; post diam., 

 0.12 mm. 



This is perhaps the most slender species known, and was obtained by Cap- 

 tain Couthouy, U. S. N., about 1850, in Samana Bay, Santo Domingo, in thirty 

 fathoms, muddy bottom, where it was abundant. It is introduced here as 

 belonging in the fauna ; the specimens have been in my hands about twenty- 

 five years. 



Cadulus gracilis Jeffreys. 



Cadulus gracilis Jeffreys (1877), P Z. S. 1882, p. 664, pi. xlix. fig. 6. 



Cadulus gracilis Jeffreys, obtained in 843 fms., off Cape Hatteras, at U. S. 

 Fish Commission Station 2115, was identified by Dr. Jeffreys as his species. 



Cadulus minusculus n. s. 



A much smaller species of Cadulus. perhaps the smallest known, was ob- 

 tained by the U. S. Fish Commission, off Hatteras, in 63 fms., sand, at Station 

 2595. It is a little stouter than C. subfusiformis Sars, but shorter and more 

 cylindrical. The mouth is decidedly more oblique than in C. subfusiformis, 

 and the shell less bent. It is much the form of C. Jeffreysi Monterosato, and 

 is just about half as large. 



May 14, 1889. 



