558 REVISION OF AUSTRALIAN LEPIDOPTERA, V. 



In the genus Apodasmia, however, the frenuhim is represented 

 ill the 5 by a strong tuft of long hairs. In C hr i/sochloroma the 

 costal dilatation is only moderate, and the (J frenulum is strong, 

 while that of the 9 is nearly obsolete. 



Di\-. iii. — Hindwing without basal costal dilatation. Frenu- 

 lum in (J strong, in 9 represented by a strong tuft of long 

 hairs. 



From this last group we may separate 



Div. iv. — Forewings with vein 10 arising separately from cell. 



Though these divisions are natural, they do not in every 

 instance represent genetic groups. I recognise at least three 

 different lines of ascent between the second and first divisions. 

 This appears of special interest as an example of a tendency, 

 within a group, to develop in a certain direction, whether the 

 tendency be regarded as innate, or as the effect of environment. 

 Between the third and second divisions there does not seem, in 

 the Australian genera, any necessity to assume more than a 

 single stem. 



Much caution and the examination of a large amount of 

 material are necessary before basing the generic definitions, in 

 this group, on variations in the neuration. The variations in " 

 vein 11, for instance, may not infrequently be found all to occur 

 within the same species. Other examples of variability will he 

 given in. this paper. • The stalking or separation of veins 6 and 

 7 of the hindwing is, on the other hand, very constant; I have, 

 so far, observed only one exce|)tion, in the genus Uliocnemis, 

 though the examination of larger material may show others. 

 Differences in the shape of the cell, more especially of the 

 discocellulars, sometimes afford valuable characters, as in the 

 genera Comostola, Argyrocosma, and Thalassodes. The shape of 

 the hind wings is sometimes a reliable generic character, but its 

 right application calls for discrimination. The variations in 

 the length of the palpi in both sexes frequently mark out natural 

 genera, but in the more primitive genus Terpnathey do not seem 

 to have attained fixity, and are, I think, of specific value only. 

 Variations in the antennae of either sex give good characters in 



