MUSEUM OF COMPARATIVE ZOOLOGY. 55 



effect of an incipient plait. Lastly the aperture extends farther behind the 

 spire than in C. alba, and, instead of the margin being curved over to a slight 

 callus sealing the apex, there is a well marked perforation, most marked in 

 the adult shells. Largest specimen 7.5 long by 3.0 mm. wide. 



Habitat. Off the coast of North Carolina, at Stations 2592, 2595, 2596, 

 2602, and 2612 of the U S. Fish Commission, in from 5U to 124 fins., sand, 

 bottom temperature 58-75° F. 



This species is larger and more cylindrical than C. umbilicata of Europe. 

 It is nearer C. cylindracea var lineata, but is shorter in proportion to its 

 width, and its body is also shorter in proportion to the whole length and more 

 obliquely attenuated to the columella. It has a striking similarity to C. alba, 

 when decorticated, until closely examined. 



The other species common to the region are C. Auberi Orbigny, C. occulta 

 Mighels, and perhaps C. cylindracea Pennant, specimens of which were re- 

 ceived from Cuming as from the Antilles (?). C. Krebsii Morch would seem 

 to be suspiciously near C. alba, but I have seen no specimens, and the locality 

 (Anguilla, etc.) seems very far south for that species. The suspicion arises 

 that the specimens may have been derived from ballast thrown overboard by 

 New England trading craft or New York fruit-carriers. 



Family BULLID^E. 



Genus BULLA Linne. 



Bulla ? eburnea Dall. 



Plate XVII. Fig. 6. 



Bulla ? eburnea Dall, Bulletin M. C. Z., IX. p. 98, 1881. 

 1 Diaphana gemma Verrill, variety. 



Habitat. Station 43, 339 fms. 



I have seen only one specimen of each of the above species, and they certainly 

 appear very different in some respects; but the range of variation in these forms 

 is little understood, and I do not feel confident that it may not be larger than 

 generally supposed. In that case it is possible that the two forms may repre- 

 sent the extremes of one species. This should not be confounded with the 

 Bulla eburnea of A. Adams, which is a member of the genus Volvula. Not pos- 

 sessing the soft parts, I have preferred to refer this species to the genus Bulla, 

 though it may belong in the preceding family. 



Bulla occidentalis A. Adams. 



Bulla occidentalis A. Adams, Thes. Conch., Part ix. Bulla, p. 577, No. 49, pi. cxxiii. 



figs. 72, 73, 1850. 

 Bulla alba Turton, Zool. Journ., II. p. 364, pi. xiii. fig. 6. 



Habitat. Antilles, in moderate depths, Adams and many others. Station 

 10, in 37 fms., Blake expedition. 



