OBELISCUS. 347 



The radula of 0. toussaintianus has 35,1,35 teeth of Steno- 

 gyrine structure. Central teeth very small, with a single 

 small cusp. Lateral teeth tricuspid, the mesocones long. 

 Marginal teeth tricuspid, with a broad mesocone and minute 

 side cusps. (PI. 25, fig. 6, 0. toussaintianus}. 



Type 0. dunkeri Pfr. ; distribution, Haiti. 



Dolicholestes differs from Obeliscus by its sinuous colu- 

 mella, and the brilliant gloss of the shell. In the structure 

 of the columella it resembles the Oriental genus Tortaxis. 

 Sigmataxis differs chiefly by its delicate, rather glassy shell, 

 marked with grooves and varix-lines. 



Mr. W. G. Binney figured the teeth of " Spiraxis dunkeri 

 Pfr." as of the aculeate type, and similar to those of 

 Streptaxida (Ann. N. Y. Aead. Sci. iii, p. 82, pi. 17, f. K). 

 I have copied his figure on plate 25, fig. 3. It was this 

 which caused me to refer the group to the Oleacinidce (Man. 

 of Conch, xviii, p. 266). On examining the radula of 

 0. toussaintianus I find that it is typically Stenogyroid. 

 This species is so closely related to 0. dunkeri in shell charac- 

 ters that they must surely belong to one and the same genus ; 

 and I am thus forced to believe that the radula figured by 

 Binney for dunkeri was some other form. 



The embryonic young of 0. toussaintianus are similar to 



0. (Stenogyra) tere/braster (Vol. xviii, pi. 37, fig. 103), but 

 with wider spire and less impressed suture. 



1. 0. DUNKERI (Pfeiffer). PI. 5, figs. 1, 2, 3. 



Shell turrite, rather thin, smooth, pellucid, glossy, tawny. 

 Spire 'elongate, the apex obtuse ; suture impressed, margined, 

 obsoletely crenulate. Whorls 9, slightly convex, 'the last less 

 than one-third the length. Columella arcuate, highly and 

 subverti'cal'ly truncate. Aperture subtriangular-semdoval ; 

 peristome simple, the right margin arched forward. Length 

 28, diaim. 7.5, aperture 9x4 mm. (Pfr.). 



Santo Domingo: Tablaso, near San Cristobal (A. Salle) ; 

 Cibao region, common, usually living in couples, under dead 

 leaves; Puerto Plata (Hjalmarson). 



Achatina dunkeri PFR., P. Z. S. 1851, p. 148 ; 1855, p. 9 ; 



