STUDIES ON THE AMPHISTOMATOUS PARASITES OF
                        INDIAN FOOD-FISHES
PART I—TWO NEW GENERA OF AMPHISTOMES FROM AN INDIAN
FRESH-WATER FISH, SILUNDIA GANGETICA CUV. AND VAL.

                                        BY

                HAR DAYAL SRIVASTAVA, D.Sc.

                Helminthologist (On special duty),
Imperial Veterinary Research Institute, Mukteswar-Kumaun.
          (Received for publication on 8th April 1938.)
       (With Plates XXIX and XXX and three text-figures.)

THE group of digenetic trematodes with a sucker at each end has received
considerable attention at the hands of Fischoeder [1901 and 1903], Stiles and
Goldberger [1910], Nicoll [1915], Stunkard [1917 and 1925], Poche [1925],
Fukui [1929], and Travassos [1934]. Recently, in July 1937, Southwell and
Kirshner have described C hiorchis purvisi which was collected from
a Malayan tortoise, Heosemys grandis, by Purvis. The joint authors, after
giving a detailed history of the classification of the group, have described the
principal characters used by various workers as the basis of classification of
this group from time to time. Finally they have proposed a scheme of classifi-
cation of amphistomes which has been adopted by the author in this paper.
In the following pages are described three new trematodes, referable to two
new genera, obtained from a common fresh-water fish in the rivers Ganges
and Jumna.

Superfamily—Paramphistomoidea Stiles and Goldberger, 1910.
Family—Cladorchidae Stiles and Goldberger, 1910.
Subfamily—Cladorchinae Fischoeder, 1901.
NICOLLODISCUS GANGETICUS, Gen. et Sp., Nov.

A number of specimens of this parasite was obtained from the large in-
testine of a fresh-water fish during the months of July to December 1934.
It is a rather rare parasite infesting on an average about five per cent of its
host. The number of specimens in a single fish varies from two to twenty.
The amphistomes are large in size and are highly muscular. The body is coni-
cal in shape with a wide, circular base formed by the posterior sucker. It is
completely devoid of spines or scales of any kind, but has well-developed
gland cells all over. In permanent mounts the body measures 9.0 to 13.4* in
length and 7.0 to 8.2 in maximum breadth which occurs across the posterior
sucker and is nearly equal to its diameter. (Plate XXIX, fig. 1).

*All measurements are in mm.

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