20 SPIRAXIS. 



ity of Ravenia, which was found on Los Roques, an islet 

 lying east of Buen Ayre anil Curagao, off the coast of Vene- 

 zuela. 



5. S. BLANDI (Crosse). Vol. I, p. 52. 



Subgenus VOLUTAXIS Strebel. 



Volutaxis STREBEL, Beitraig zur Kenntniss Mexikanischer 

 Land und Siisswasser Conchylien v, p. 110 (1882), first 

 species V. sulciferus. 



Shell imperforate, turrite, thin, vertically striate or ribbed, 

 glossy, whitish-corneous or pale yellow ; whorls 5 to 13, slowly 

 increasing, the first I 1 /-} forming a smooth obtuse summit. 

 Aperture small, the outer lip thin and simple, arcuate, the 

 columella spirally twisted (or sometimes nearly straight), 

 slightly thickened, not truncate. 



Type 8. sulciferus Morelet. 



Part of the species have already been treated of by Tryon 

 in vol. I of 'this work. The others known: up to this time are 

 described below. 



In Volutaxis the shell is less specialized than in typical 

 Spimxis; the whorls are shorter and more convex than in 

 Sigmataxis. All the Spiraxes known from Mexico and Central 

 America belong to this group, together with a few from 

 Jamaica, Cuba and Haiti. Some East Mexican forms 'diverge 

 from the typical Volutaxes by having a nearly straight colu- 

 mella, not perceptibly sinuous; and a few (species 21 to 23) 

 are distantly grooved, also with the columella straight. The 

 generic place of these species is uncertain; but they surely 

 dio not belong to Opeas, where some of them were originally 

 placed, and the straight columella removes them from 

 Sigmataxis. 



I. Mexico and Central America, species 6 to 29. 



II. Cuba, species 30. 



III. Haiti, species 31. 



IV. Jamaica, species 32, 33. 



