Fluviatile Mollusca of Trinidad. 45 
and scarcely closed, and consists merely of an extended fold of 
the neck-lappet. 
A smaller variety occurs in some places. While in the type 
the spire is depressed below the level of the last whorl, in the 
variety the apex is slightly above that level. I propose to call 
this variety Swiftz, after Mr. Swift, of St. Thomas, who, amongst 
many other valuable hints, pointed out to me the differences in 
these shells. 
Marisa cornu-arietis prefers ponds and the more quiet streams, 
as might be inferred from the shape of its shell, which does not 
enable the animal to resist a strong current so well as the 
globular shells of the Ampullarie. It is therefore less common 
in mountain-streams. Its capability of resisting drought is also 
very much less than that of A. urceus and A. effusa. 
The lingual dentition is 3.1.3, as in Ampullaria. The 
central tooth has three dentations on each side of the strong, 
acute apical point. The mandibles are similar to those of Am- 
pullaria effusa, but thinner and weaker. The eggs are deposited 
in jelly-like masses on twigs, &c., in the water. The young: 
mollusks, when hatched, are imperforate and subglobose, very 
similar to the young of A. e/ffusa. 
ADAMSIELLA, Pfeiffer. 
Adamsiella aripensis, Guppy. 
(Ann. & Mag. Nat. Hist. ser. 3. vol. xiv. p. 246.) 
This mollusk lives principally among the dead leaves on the 
ground in the forests. It frequently suspends itself by two or 
three glutinous threads from branches on the under surface of 
leaves at a height of one or two feet from the earth. 
Cyctorus, Guilding. 
In my former account* of the two species of this genus in- 
habiting Trinidad I did not give a full description of the animal, 
because I was under the impression that naturalists were suffi- 
ciently acquainted with the general characters of the genus. 
But I find that Mr. W. T. Blanford+, observing that certain 
Indian species have a divided foot like Cyclostoma, has pro- 
posed for them the generic name of Cyclotopsis. He is also of 
opinion that the American species should be classed with Cyclo- 
stoma. 
The animal of Cyclotus translucidus, Sow., is of a pinkish 
colour, light about the body and foot, but deep on the tentacles ; 
the foot is broad, undivided, and obtusely pointed behind; the 
tentacles subulate ; the eyes small, black, and sessile at the bases 
* Ann. & Mag. Nat. Hist. ser. 3. vol. xiv. p. 245. 
+ Ibid. vol. xui. p. 446. 
