CERCARIA HURLEYI, N. SP.

                                                    BY

                                    M. ANANT NARAYAN RAO,

                   Lecturer in Parasitology, Madras Veterinary College.

                     (Received for publication on 8th April 1933.)

                                           (With Plate XX.)

This pharyngeal longifurcate cercaria was obtained from seven snails of the
species Limnea leuteola (Lamarck), out of 710 collected from the Spur tank, Egmore,
during the last quarter of the year 1931. This kind of larval trematode has not
been found in any other kind of fresh water snails collected from the Spur Tank.

The cercariae occur in long slender sporocysts in the digestive gland of the
snail, and often the sporocyst wall is seen bulging in places in which a large number
of cercariae are massed together. It was not possible to obtain a complete
sporocyst, but it would appear that the larvae escape by bursting open the wall at
the bulges.

The cercariae that were discharged by the snail in water were chosen for study.
Each larva is a powerful swimmer, though small in size. It appeared to be nega-
tively phototrophic. The body is an elongate cylinder measuring 1.0 × 0.04 mm.
The tail stem is 0.08 × 0.02 mm., and each furcal ramus is 0.15 mm. in length.
The body and tail are spinose. The cercaria has two pale yellow eye spots, in
front of the ventral sucker. On the body there are four setae on each side,
and on the tail there are six of such setae. Each seta originates from a refractile
granule. In the body there are two suckers. The oral sucker, with its pile of
circular muscle fibres, simulates a protrusible anterior penetrating organ. The
ventral sucker, which is a little wider in diameter than the other, is situated a little
behind the middle of the body. It is well developed and its cuticular lining is
armed with three rows of short and stout spines.

The alimentary canal is well developed. There is a short prepharynx, a small
muscular pharyngeal bulb, followed by a long œsophagus of a thin calibre, and this
bifurcates in front of the ventral sucker into two intestinal ceca which reach almost
to the posterior end of the body.

There is a pair of small penetration glands on either side of the ventral sucker,
on its anterolateral aspects. The anterior gland is the larger of the two, in each set,
and contains coarsely granular oxphilic contents and the posterior gland has fine
granules basophylic in reaction. The ducts from both these glands pass forwards

                                                    (237)