SOUTH AMERICAN OPEAS. 207 



whorls, but it is much more slender, with relatively larger em- 

 bryonic whorls, and rather flat, little convex, proportionally 

 lower whorls, at the same time having a distinctly marked 

 suture. The sculpture is very inconspicuous, and hence the 

 shell is rather glossy. The columellar reflection is distinctly 

 developed, leaving an umbilical slit, and it has a thickening on 

 the inner side below " (Strebel). 



Strebel figures also a smaller form, 9.5 mm. long with 7y 2 

 whorls, also from Venezuela. Fig. 79 is a copy of Strebel's 

 photographic figure of the type of octogyrum. 



Stenogyra plicatella Guppy is identical with octogyrum, or 

 at most may be distinguishable as a local variety. The de- 

 scription follows. 



Var. plicatellum Guppy, (pi. 29, fig. 75). "Shell subu- 

 late, long-cylindric, subperforate, corneous, a little shining, 

 sinuously striate; whorls 8 to 9, slowly increasing, a little 

 convex, the last swollen; suture strong; aperture long, oval; 

 peristorne simple, a little sinuous above, the margins joined 

 by a thin callus; columella straight, widely reflexed over 

 the umbilicus. 



" Length 13, diam. 3.5, height of aperture 3 mm. 



"Length 15, diam. 3.5, height of aperture 2 mm. 



"Length 9, diam. 2, height of aperture 1.5 mm." (Guppy). 



Trinidad (Guppy, type loc.) ; Grenada and St. Vincent 

 (Guppy, H. H. Smith) ; St. Lucia (Tate). 



Bulimus octonoides GUPPY, Ann. Mag. N. H. (3), xvii, 

 1866, p. 50, not of Adams. Stenogyra plicatella GUPPY, Ann. 

 Mag. (4), i, 1868, p. 434; Proc. Scient. Asso. Trinidad 1869, 

 p. 239; Journ. of Conch, vii, 1893, p. 213; P. Z. S. 1875, p. 

 320. Bulimus p., PFR., Monogr. viii, p. 137. Opeas plicatella 

 Guppy, CROSSE Journ. de Conch. 1890, p. 45, pi. 2, f. 2. 

 SMITH, Proc. Malac. Soc. Lond. i, p. 308, 317, pi. 21, f. 15; 

 Journ. of Conch, viii, p. 236. 



In 0. octogyrum the whorls are much flattened, especially 

 the later ones, and they are very oblique, the individual whorls 

 being very high. The striation is weak, quite unlike 0. subula 

 (gracile), consisting of arcuate irregular wrinkles of the very 

 glossy surface. The axis is faintly visible through the shell. 



