240 Records of the Indian Museum. [VOu. V, 1gto.] 
the exception of a few showers in January) rainless. It seems 
unlikely, therefore, that a large variety of forms should ever be 
discoverable in this neighbourhood. 
I am in complete agreement with Piguet when he says, ‘‘ pour 
distinguer stirement les Navs indiennes les unes des autres, et pour 
établir leur rapports avec les espéces deja connues, il faudra étudier 
a fond leur appareil génital.’’ But it is improbable that any more 
material from the same source as that described in the present 
paper will reach me, and the chances, in any case, would be 
against its including any sexual specimens; as Piguet says, ‘‘a 
moins d’une chance rare, ce n’est qu’en pourstiivant ses recherches 
pendant des années, en toute saison et dans des milieux aquatiques 
aussi variés que possible, qu’on peut espérer se procurer un 
matériel de Naididées sexuées permettant une étude un peu appro- 
fondie.” It seemed better, therefore, to give the above descrip- 
tions as they stand. 
The position, briefly, is this. Nats communis, var. punjabensis, 
has been shown by its sexual organs to be closely related to N. com- 
munis; and this is expressed by making it a variety of this latter 
species, though its setae have, on the whole, a greater resemblance 
to those of N. variabilis. JI have examined a form with eyes from 
Travancore, which, as far as can be ascertained, is so similar to 
the above mentioned variety from the Punjab that it appears mere 
hair-splitting to separate them. A form without eyes also occurs 
along with the last, identical with it, it would seem, in every 
other respect, so far as can be seen from an examination of the 
available material. If the Travancore form with eyes is a variety 
of N. communis, then so will be this latter. But these conclusions 
will be subject to revision in case sexual specimens become avail- 
able for examination. 
Se Oreo. 
