22 Records of the Indian Museum. [VoL. XVIIE, 
Limnaea were observed in great abundance in November, Decem- 
ber and January, and in females killed at this time of the year 
the female part of the reproductive organs was found to be in a 
state of activity. No individuals were, however, observed paired, 
and the male part of the hermaphrodite gland seems to be aborted. 
It is probable, therefore, that Limnaea is protandric in the pecu- 
liar conditions which exist in Seistan and Baluchistan, that pairing 
takes place in summer, and that the spermatozoa are stored up for 
considerable periods. 
PARASITES AND INCOLAE. 
The main object of the tour on the collections of which this 
paper is mainly based was to discover what could be discovered 
about the distribution of the aquatic molluscs and their trematode 
parasites in reference to the etiology of the disease Bilharziasis or 
Schistosomiasis. Living molluscs were examined in the field by 
Mr. S. W. Kemp, who has been kind enough to supply us with 
the following information. His examinations were made in Nov- 
ember and December. 
The only molluscs in which trematodes were found in water 
brackish to the taste was Melanoides pyramis var. flavida. Of 
twenty-five individuals of this form from a small water-course at 
Saindak in the western part of the Baluchistan desert one was 
infected by the voung rediae (indeterminate) probably of a Xiph- 
idocercarta. ‘The water was potable but tasted salt and bitter. 
Sixty specimens of Limnaea gedrosiana from the reed-beds 
of the Hamun near Lab-i-Baring were examined and none found 
infected. Of another sixty of the var. rectilabrum of the same 
species from a small pool in the desert near Nasratabad only one 
was parasitized, its parasite being a small cercaria of the family 
Schistosomatidae. One hundred specimens of L. bactriana (fifty 
of the long-spired and fifty of the short-spired form) were examined 
at Nasratabad, from an irrigation channel. Ten contained tre- 
matode cercariae; in eight of these the parasite was a large 
monostome, while in one it was a Schistosomatid (apparently the 
same species found in L. gedvosiana) and in one the infection was 
a mixed infection of these two parasites. 
Seventy-four specimens of Gyvaulus convextuscuius from the 
reed-beds of the Hamun were examined and seven were found 
infected by Trematodes, two by indeterminate elongate sporocysts, 
three by Schistosomatid cercariae without eyespots and two by 
similar fork-tailed cercariae with eyespots. Only two specimens 
of Gyraulus euphraticus were examined, from the same locality; 
one was uninfected, while the other contained Schistosomatid cer- 
cariae without eyespots, apparently of the same species as was 
found in G. convexiusculus. 
The Schistosomatid cerearia found in aquatic Pulmonate 
molluscs in Seistan does not appear to belong to any of the 
species known to parasitize man. A liver-fluke of the genus 
Fasciola (s.s.) is common in that country, but its cercariae were 
