466 Journ. of the Asiat. Soc. of Bengal. [Nov. & Dec., 1915. 
we find the well-marked endemic variety elongata occurring 
with the typical tuberculata. It i 
illustrating the adaptability in habits possessed by M. tuberculata 
that, whereas in the Lake of Tiberias it lives in compara- 
tively deep water and is rarely found at the margin, in Cal- 
cutta ponds it swarms at the edge and rather avoids the central 
parts. 
Amongst the amphibious Palaeotropical forms included in 
the Tiberias fauna there are several insects, for example the 
bug Rhagovelia nigricans and some of the dragon-flies. In 
the latter forms, however, the relationship is generic rather 
than specific. 
these facts it seems legitimate to conclude that 
the Palaeotropical element, whether its origin be froni the 
east or from the west, consists of species or genera that have 
peculiar powers either of withstanding changes in environ- 
aes or of making their way from one body of water to an- 
other. 
Considering the presence of African fish, it may further 
be regarded as probable that the Palaeotropical element is 
mainly, if not entirely, of African origin so far as true aquatic 
form are concerned, though some of the insects have probably 
come from the East. All that can be stated against this view is 
the presence of the fish Discognathus in the Jordan and its 
Oligochaete worm Criodrilus lacuum,! which, however, is also 
fish’s peculiar habit of clinging by means of an oral sucker to 
living bodies in the water near it may have assisted in “ 
distribution and it is probably that like many of the family 
i Ae 
Apart from any tropical element in the Jordan fauna, there 
be of African origin, though not 
have made thei 
elr way for some little distance overland. Its 
any case so remarkable that a further investigation is necessary. cea 
Stephenson, Mem. Ind. M. (1915) 
