224 BULLETIN OF THE 



body whorl, as exemplified in various gradations by the several species, — all 

 these reasons call lor more thorough determination of all the facts to be con- 

 sidered for each species, before the transfer is fully adopted. 



Tryon states, in his monograph of Ranella, that Apollon gyrinus Montfort is 

 Ranella gigantea Linne, which is, of course, entirely inaccurate, as a glance at 

 Montfort's figure is sufficient to prove. 



The number of species actually inhabiting the Antillean region is disputed, 

 and I have not the material to determine it. The sculpture and size are ex- 

 tremely variable. 



Gyrineum affine Broderip var. cubanianum Orbignt. 

 Ranella affinis Broderip, P. Z. S. 1832, p. 179. 



Habitat. Off Havana, Sigsbee, in 80-100 fms. (dead shells of the very 

 young). Cuba, Arango, Orbigny. Arrowsmith Bank, Yucatan, and off Key 

 West in 50 fms., coral, U. S. Fish Commission. 



All the shells I have seen from the Antilles under the names of Ranella 

 cubaniana Orb., ponderosa Reeve, (homos. Orb., crassa Desh., granulata Lam., 

 gram/era Lam., Grayana Dkr., livida Reeve, and rhodostoma Beck, have been 

 referable to varieties, more or less pronounced, of Gyrineum affine, and are en- 

 tirely indistinguishable from similar varieties brought from the Indo-Pacific 

 region. I would not be understood as asserting that but one species is found 

 in the West Indies, but, so far, I have seen no conchological evidence for more 

 than one. 



The larval shell of this species is extremely pretty, and worthy of description, 

 since it is usually lost or eroded at an early period. It consists of a narrowly 

 umbilicated naticoid shell of three and a half whorls. The nucleus is very 

 small, smooth, and formed of half a whorl abruptly differentiated from the 

 next stage, which has three spiral keels with the interstices beautifully decus- 

 sated by elevated sharp oblique transverse lines. The keels gradually fade 

 out, and the last whorl and a half are polished, with traces of the transverse 

 sculpture. The whole is of a fine warm brown color, lighter toward the apex. 



The numerous whorls and the indications of a regular growth in this larval 

 shell, continued for the greater part of its coil, show that the larval period is 

 prolonged. The well known ability of the floating larvae to sustain themselves, 

 like Pteropods, near the surface, and the. length of time during which this may 

 continue, afford a sufficient explanation of the world-wide distribution, in warm 

 latitudes, of the species of this family. The young may easily be taken for 

 adult shells, and the genus Brugnonia of Jeffreys, among others, has been 

 referred to the larva of a mollnsk of this sort. 



The Ranella anceps, hastula, and their allies, do not belong in this genus. 



March 18, 1889. 



