the Lepidopterous Family Cossidae. 



167 



and hind-wing neuration, and (b) those with unlike neura- 

 tion of the two wings, the number of the veins in the 

 hind-wings being considerably reduced. For these two 

 groups I accept the names proposed by Mr. R. J. Tillyard 

 in a short but illuminating paper (Proc. Linn. Soc. N.S.W., 

 1917, p. 167) of Lepidopiera Homoneura and Lepidopiera 

 Heteroneura, These names are preferable to Jugatae and 

 Frenatae, for the number of the veins is of more importance 

 than the presence or absence of the frenulum, and as the 

 latter organ is present in two other orders of insects besides 

 the Lepidopiera. namely, the Meeoptera and the Neuroptera 

 Planipennia (Tillyard, I.e., p. 174), it is probably more 

 primitive than has been supposed, and its absence in the 

 Lepidopiera Homoneura may well have been due to loss.* 



The Lepidopiera Homoneura consist of the Micropterygidae 

 and Erioeranidae (if these are really lepidopterous) and the 



Hepialidae. I regard them as offshoots of the primitive 

 lepidopterous stem and not as part of the main line of 

 development, as illustrated in the accomj^anying diagram. 



The dotted line represents the present era. Deeply 

 beneath it is the primitive lepidopterous stem, three 

 branches of which reach the surface ; A represents the 

 Micropterygidae and Erioeranidae, B the Hepialidae, and 

 C the Lepidopiera Heteroneura. There is no evidence that 

 the two former were ever more numerously represented in 

 previous eras than at present, though that is quite possible, 

 but the third are a dominant group at the present day, 

 consisting of a vast number of genera and species, and are 

 consequently represented by a wide-based inverted cone. 



The structure of the Lepidopiera Homoneura is of great 

 interest in the evolution of the order, but has small con- 

 nection with the object of the present essay, the natural 



* Mr. Tillyard has since this was written sent me a drawing and 

 photographs Remonstrating that a frenulum is actually present in 

 the Micropterygidae. 



