62 Records oj the Indian Museum. [ VoL. <VELE, 
and parasitic life, it is improbable that the shell would grow 
25 mm. in one season, and we take it that these young shells repre- 
sent the growth of something more than a year, probably about 
eighteen months. The second region probably represents that of 
one year more, but does the third region correspond to the growth 
of one year or of six? Probably of one, to judge from the striae 
on a large series of shells. If this be so, Lamellidens marginalis 
yhadinaeus probably lives as a rule for a little over three years and 
then dies directly or indirectly of old age. The great majority of 
the shells collected must, if our surmises are correct, have been of 
this age, and the animals through weakness ot for some other 
reason, have failed to burrow down to the subsoil water through 
the very stiff clay on the bottom of the basins in which they lived, 
when the water began to dry up with the retreat of the floods. 
NOTE ON THE LIVER-FLUKE OF SHEEP IN SEISTAN, 
By STANLEY Kemp, B.A. 
When in Seistan we were informed that both sheep and cattle 
are frequently infected by a liver-fluke which causes a heavy 
mortality at certain places in the early summer of each year. On 
enquiry we learnt that the Seistanis associated this parasite with 
the fact that when the annual floods recede the flocks are grazed on 
the peculiar vegetation that springs up on recently inundated land. 
I was able (in December) to examine the livers of three sheep, 
the bile-ducts of two of which contained flukes of the genus 
Fasciola, s.s. In one of the livers the worms were unfortunately 
dead and in a putrefying condition. The other contained eleven 
specimens, all of which were alive. 
Unfortunately the literature on this genus is poorly repre- 
sented in our Calcutta libraries and several important American 
memoirs on the subject are lacking. Notwithstanding this fact, 
however, there appears to be little doubt as to the specific identity 
of the Seistan form, for most of our specimens agree in every parti- 
cular except size with the excellent figures of Cobbold’s Fasciola 
gigantea, reproduced from Looss by Stevens in ‘‘ The Animal Para- 
sites of Man (London, 1916). 
The chief characters by which this species is distinguished from 
Fasciola hepatica are the following :— 
(i) The form is generally much more elongate and band- 
like instead of leaf-shaped, the tapering of the pos- 
terior extremity being confined to a very small area. 
(ii) The cephalic cone is considerably shorter in proportion 
to the length of the whole organism. 
(iii) The posterior sucker is larger and more prominent and 
is situated on a line with the junction of the cephalic 
cone and body, instead of well behind the cone. 
