BY R. J. TILLYARD. 377 



partially succeeded in casting its old skin. The small water-fleas, 

 too, had apparently partly destroyed its caudal gills, so that I 

 was glad I had already made a sketch of them. Considering 

 liow very different both the food and the habitat of my artificially 

 raised nymph were from those it would have had in a state of 

 nature, it was scarcely to be expected that I could obtain a full- 

 fed specimen. Possibly a diet of infusoria and small water-fleas 

 miy have been the cause, in the end, of its failure to undergo 

 €cJysis; or living in stagnant water instead of a swift mountain 

 stream may have been suflicient to prevent the full use of its 

 strong muscular limbs, and so weakened it physically. I was 

 fortunate, indeed, in keeping it so long alive and in being able to 

 sketch the caudal gills and antennse of the young larva. 



To complete the life-history, it was necessary to find either the 

 full-grown larvjc or the exuviiTe. I doubt if it is possible ever to 

 obtain the first, for I judge from my observations of the young 

 larva that it probably lives in the crevices of the solid bed-rock 

 of the stream, and is active enough to retreat rapidly away from 

 any not or instrument used to snare it. Of the exuviae I was 

 fortunate enough in obtaining four, as the result of examining, 

 for a whole day, rocks and boulders in the bed of the stream in 

 the Rodriguez Pass, Blackheath, N.S.W., on November 7th, 

 1908. I found them clinging to the rock-surface, in company 

 with a large number of ephemerid exuvise of smaller size. The 

 claws of the tarsi had such a firm hold of the rock that it was 

 v>^ith the greatest difficulty that they could be detached without 

 ■ damage. I recognised these exuviae at once as being similar to 

 that found at Heathcote. Two of them also possessed shrivelled 

 remains of caudal gills. An examination of antennae and labium 

 showed that they were the same species as the small larvae bred 

 from the Heathcote ova; in fact the latter, even in that early 

 stage, showed a very close resemblance to the exuviae in general 

 form. As Diphlebia lesto'ides was the only zygopterous dragon- 

 fly to be found along the Rodriguez Pass, where it is fairly com- 

 mon, I now felt quite certain that I had the exuviae of that 

 ijpecies, a full description of which I append. 



