1921. ] S. Kemp: Larval Trematodes. 231 
The cercariae develop in rediae which, as in those of Fasciola 
hepatica, bear a pair of processes near the hinder end ; they reach 
a maximum length of about 2°5 mm. 
Cercaria A was found in specimens of Limnaea bactriana, 
Hutton, living in small irrigation channels close to the British 
Consulate at Nasratabad in Seistan. Of one hundred molluscs 
which were examined for parasites nine contained this Cercaria. 
Cercaria B (text-figs. 1 d, e). 
This is a furcocercous form which appears to resemble rather 
closely the larva of Schistosoma japonicum as described by Cort.' 
The body in well-preserved specimens is from 167 to 193» in 
length and the mean of a number of observations is 186. Its 
breadth varies from 41 to 52, the mean being 48. The undivided 
part of the tail is from 192 to 222, with mean of 208; the furca 
are from 62 to 67 , with mean of 64h. 
The oral sucker is from 31 to 33, in diameter and the 
acetabulum from 22 to 23 p. 
The alimentary canal appears to be altogether absent and the 
body is for the most part filled with large gland cells (figs. I d, e). 
The four anterior gland cells differ very decidedly in character 
from the remainder, for in preparations treated with eosin the 
posterior cells are always very heavily stained, while the four 
anterior remain colourless. No ducts leading forwards from the 
four anterior cells could be traced in preserved material, though on 
analogy with similar forms it is probable that they really exist. 
The ducts from the posterior cells stain readily with eosin and are 
very conspicuous. ‘The number of posterior cells appears to be six, 
making five pairs of cells in all; but two are usually concealed by 
others which overlie them. 
On either side of the ducts from the gland cells, in the 
anterior half of the body length there is a small semitransparent 
area which perhaps represents an unpigmented eye-spot. _ Poster- 
ior to the acetabulum the beginnings of the gonad are visible, 
consisting of a mass of cells which is usually crescentic in form 
when seen in dorso-ventral view. 
This cercaria, so far as can be seen from preserved material, 
seems akin to that of Schistosoma japonicum or, more nearly, 
to the very closely allied form from Bengal recently described 
by Major Sewell (loc. cit.). There are, however, marked differences. 
In the Seistan cercaria the tail-flukes appear proportionately 
shorter, the acetabulum larger and unpigmented eye-spots are 
perhaps present. No trace of the gut could be found, nor of teeth 
on the anterior sucker. 
Cercaria B was found in specimens of Gyraulus convexiusculus 
(Hutton) obtained in the Hamun-i-Heimand, Seistan. Forty-three 
! Cort, Univ. Calif. Publ. Zool., XVIII, p. 485 (1919) ; see also Sewell, 
Rec. Ind. Mus., XVI, p. 425 (1919). 
