Fluviatile Mollusca of Trinidad. 53 
STREPTAXIS, Gray. 
Streptaxis deformis, Fér., sp. 
The animal is of a delicate pink or yellow colour; and it is 
found both on trees and on the ground m the woods. _ Lingual 
teeth 10.0.10, aculeate. Judging by the teeth, no Jess than 
by the form of the immature shell, Séreptawis would be classed 
nearer to Zonites than to Helix. The teeth are all simple, like 
those on the lateral portion of the dental membrane of Zonites 
cellarius; but in Streptaxis deformis they are longer, and have 
narrower hases. 
Simputorsts, Beck. 
Simpulopsis corrugatus, n. sp. 
Shell imperforate, subglobose, very thin, membranaceous, some- 
what flexible, greenish hyaline, corrugated by stout, rather 
irregular, longitudinal ribs; suture linear; spire small, con- 
vex ; whorls 4, convex, rapidly increasing, the last one forming 
the greater portion of the shell; aperture large, rather oblique, 
rounded; peristome simple; columella arcuate. Height 
0:38 inch, greatest breadth 0°47 inch; height of aperture 
03 inch, breadth of aperture 0°25 inch. 
Animal gyveyish-brown ; tentacles four; eyes on the upper 
pair. Mantle-edge narrowly reflexed over the peristome. I 
regret having been unable to examine the teeth of this mollusk, 
the only three examples I found having decomposed before I 
had an opportunity of preserving the soft parts. 
This species comes nearest to S. brasiliensis. The aperture is 
more nearly orbicular, and the ribs larger than in S. rufovirens. 
The shell is less Swecinea-shaped than that of S. braszliensis. 
Conutus, Moquin-Tandon. 
Conulus vacans, n. sp. 
Shell small, trochiform-depressed, subperforate, thin, fragile, 
pellucid, shining, brownish horn-coloured ; whorls 5, carinate, 
flattened and obliquely striate above, closely covered with fine, 
longitudinal, rather wavy striz, visible under a lens, and most 
distinct on the polished under surface ; spire conoidal; aper- 
ture lunate; peristome simple, acute; columellar margin 
slightly reflected. Greatest diameter 0°18 inch, height 
0:12 inch. 
The animal has four stout tentacles. Mantle filling the aper- 
ture and projecting, but not reflected over any part of the shell. 
Foot narrow, truncate, with a small retractile appendage on the 
truncate tail. g organ stout, on the right side, below and a 
little behind the upper pair of tentacles. The foot has a median 
