1gIQ. | N. ANNANDALE & B. PRasHAD: Mollusca. 23 
not found, probably because their incidence is seasonal. Mr. 
Kemp has given us a note on this species (f. gigantea) which is ap- 
pended to our paper. He hopes to describe all other parasites later. 
Small red nematodes were common in Gyvaulus convexiusculus 
in the Hamun in December. 
The Oligochaete worm Chaetogaster was found in abundance 
at the edge of the mantle and in the branchial chamber of Lim- 
naea gedrosiana var. rectilabrum in a pool in the desert near Nasrat- 
abad in the same month. Col. Stephenson has identified the worm 
as Ch. bengalensis, Annandale, a species common in Northern India. 
SYSTEMATIC ACCOUNT OF THE FAUNA. 
Class GASTROPODA, 
Fam. HYDROBIIDAE. 
1915. Paludestrinidae, Preston, Faun. Brit. Ind., Freshw Moll., p. 67, 
1919. Paludestrinidae, Godwin-Austen, Rec. Ind. Mus. XVI, p, 209. 
Genus Amnicola, Gould and Haldeman. 
1865. Amnicola, Stimpson, Smiths. Misc. Coll., 201, p. 12. 
The excellent account of this genus given in the work cited 
enables us to relegate to their proper genus certain Indian, 
Burmese and Persian species that have usually been placed in 
Bithynia. These species, however, differ in some respects from 
the American forms—sufficiently in our opinion to be regarded as 
constituting a new subgenus, for which we propose the name :— 
Subgenus Alocinma, nov. 
The shell agrees precisely with that of the American A mnicola 
and the Palaearctic Pseudamnicola, being globose or subglobose 
or slightly elongate, imperforate or subumbilicate, small, thick 
and smooth, with swollen whorls and having its mouth oval or 
ovate with a continuous but not greatly thickened peristome. 
The animal has a relatively short foot, which projects very little 
if at all beyond the shell. It is rounded or pointed behind and 
angulate in front. The snout is long and narrow. ‘The tentacles 
are hardly longer than the shell, thin and filiform, and bear the 
eyes, which are small, at their base externally. The edge of the 
mantle is simple. The penis is large, flattened, lunate in outline 
and provided with a long and stout lateral process, which projects 
on the left side from its concave margin almost at right angles. 
It is situated almost in the middle of the ‘‘ neck.’’ The opercu- 
lum 1s of large size, and incapable of withdrawal into the shell, 
thick and calcareous but usually hyaline or subhyaline, distinctly 
spiral and with a siightly eccentric nucleus, but ornamented round 
the margin with concentric lines. ; 
