358 BULLETIN OF THE 



Barbados, in 73 fms., coral and shell, bottom temperature 70°. 75. U. S. Fish 

 Commission Station 2602, in 124 fms., sand, thirty-six miles S. | W. from 

 Cape Hatteras, North Carolina, bottom temperature 61°. F. 



The operculum is like that of Gaza, and has six or seven whorls. None of 

 the specimens show any tendency to a reflected lip, yet it is, of course, possible 

 that no completely adult specimen was obtained. The animal has a short 

 stout foot, bluntly rounded at either end. It is of a pinkish tint. The ten- 

 tacula are very long and the eyes large. The muzzle is rounded and not very 

 long, its extremity plain. There are no frontal lobes. The epipodium has a 

 very small anterior lobe with a cirrus behind it, then a space without cirri, a 

 long process just in front of the opercular disk, and one, shorter, under it on 

 each side, making three in all. There is no posterior point to the epipodium, 

 and only the above three cirri on each side. The jaw is somewhat like that of 

 Umbonium, but shorter and broader. The radula, however, bears no resem- 

 blance to that of Umbonium {Rotella Lam.). The teeth are very elegant. 

 The rhachidian tooth in general form (except the cusp) not unlike that of 

 Calliostoma granulata Born (Troschel, II. pi. xxiv. fig. 18), but the central 

 spur of the cusp is long and slender like a stiletto, extending considerably be- 

 hind the posterior edge of the base of the tooth. On each side of it are four 

 stout sharp rather short denticles, radiating as from the median point of the 

 front edge of the cusp. The laterals recall those of Gibbula divaricata (Tros- 

 chel, he. cit., fig. 6), but have more, larger, and stronger denticles, all on the 

 posterior edge of the cusp, or the edge away from the rhachis. The uncini are 

 rather few in number, the cusps sword-shaped, sigmoid, the inner ones den- 

 ticulated on both edges. The number of laterals is five. The radula as a whole 

 is very short and small. 



The depressed form and marginated suture, as well as the kind of coloration, 

 in this shell recall Umbonium. The texture of the shell and the character of 

 its umbilicus are precisely as in Callogaza. The soft parts indicate its place to 

 be in that vicinity. Until a larger number of the myriad of species shall have 

 been examined, it is evident that the characters of the dentition in their classi- 

 fication cannot be formulated except in a provisional manner. 



Trochus solarioides of Seguenza, from the Reggio Tertiary, seems to be a 

 Microgaza. 



Genus UMBONIUM Link. 



Umbonium Link, Beschr. Rostock iSamml., 1807, p 136. 



Rotella Lamarck, 1822. 



Helicina Gray (non Lamarck), 1847. 



After a careful examination of the literature, I see no reasonable ground for 

 the assertion of Gray (P. Z. S. 1847) that Helicina of Lamarck (1801) was 

 identical with his Rotella of 1822, or different from his Helicina of 1822, such 

 as we are accustomed to understand by the latter name. The original diagno- 



