TWO NEW MONOSTOMES (TREMATODA) FROM AVIAN HOSTS IN BRITISH INDIA.
51
The main portion of the excretory system consists of a short bladder that divides
into two main lateral branches behind the ovary. The excretary pore is median
and is situated on the dorsal side of the body near its posterior end.
DISCUSSION
From the foregoing description it is quite evident that the worm is a digenetic
trematode belonging to the superfamily Notocotylidæ, family Notocotylidæ and the
genus Notocotylus. Up to the present time sixteen species of this genus have been
recorded ; these being N. attenuatus, N. ægyptiacus, N. chionis, N. gibbus, N. intes-
tinalis,N. naviformis, N. noyeri, N. quinqueserialis, N. seineti, N. trachyeretis, N.
urbanensis, N. discrialis, N. thienemanni, N. parviovatus, N. magniovatus and N.
vespertilionis. Of these species the last named, coming as it does, from a mamma-
lian host, will not be considered in the present discussion. All the remaining species
have been recorded from avian hosts. Of these the species N. diserialis has been
regarded by Sprehn [1932] and Kossack [ 1911 ] to be very poorly described' and
its inclusion in the genus Notocotylus is highly sceptical. In regard to the species
N. ægyptiacus both Odhner [1905] and Kossack [1911] remark that it is not
possible to understand how it differs from the species N. attenuatus and N. gibbus.
Of the two recently described species : N. parviovatus and N. magniovatus, the
latter in the opinion of the writer is identical with N. attenuatus and should be
regarded as its synonym. Even according to the original author Yamagati [ 1934 ] ,
the only point of difference between N. attenuatus and N. magniovatus is the size
of the eggs. This difference is not sufficient to separate one species from the other.
Moreover, if we compare the measurements of the eggs of N. attenuatus and N .
magniovatus they are 0.02—0.022 × 0.01 : 0.024—0.027 × 0.01—0.012. These
measurements do not indicate any outstanding difference between the supposed
two species. Baylis [ 1928 ] does not attach any importance to the number of
ventral glands in each row. He is inclined to the view that ventral glands increase
with the age of the parasite. Although the writer had no opportunity to verify
this view it is not thought advisable to introduce this debatable point in the dis-
cussion to follow. On comparing the species under report with the remaining
ones in a tabular form it has been found that it can be differentiated from N. quin-
queserialis on account of the possession of only three rows of the ventral glands.
N. naviformis has the genital pore anterior to the intestinal fork. The species N.
noyeri, N. chionis and N. tachyeretis have their cirrus sac reaching the mid-body.
From N. urbanensis and N. thienemanni it differs in respect of the units in the rows
of the ventral glands. The species N. gibbus, N. seineti and N. intestinalis have
their vagina much longer in comparison to the cirrus sac. The species N.
parviovatus differs in the comparative size of the vagina and cirrus sac, the number
of ventral glands in each row and the extent of the vitellaria. It has, however,
got much affinity to the remaining species, viz., N. attenuatus. It agrees with it in
the rows of the ventral glands and their number in each row, the nature and
situation of the genital glands, the posterior extension of the cirrus sac and also in
the relation of the latter to the vagina. It, however, differs from it in the position
D 2