BY R. J. TILLYARD. 127 



It is thus very evident that a single type of wing-coupling 

 apparatus characterises the Micropterygince and Mnesarchceince, 



the latter being, as regards this character, an asthenogenetie 

 offshoot from the former. The Eriocraniince, on the other hand, 

 have a jugal lobe resembling that of Rhyacophila. Thus we are 

 placed in somewhat of a dilemma: since, on the characters of the 

 wing- venation and mouth-parts, Mnesarchcea would appear to be 

 an offshoot of the Eriocraniince', while the latter, judged by 

 these same characters, are not so archaic as the Micropterygincet 

 and hence should be further removed from Rhyacophila, if a 

 Trichopterous origin for the family is to be maintained. 



Section iv. Discussion of the Results. 



We have now to consider the bearing of the results of our 

 study of the wings of the Micropterygidce upon the systematic 

 position of the group We may best do this by asking the 

 following questions in order, and answering them from the evi- 

 dence now available : — 



(1) Are the Micropterygidce, or any part of them, rightly to be 

 considered as forming a separate Order Zeugloptera ? 



Dr. Chapman's new Order Zeugloptera includes only the genus 

 Micropteryx. But it will be evident that, if it is to stand at all, 

 it must also include the genera Sabatinca and Micropardalis; 

 since these are so closely allied to Micropteryx, that any attempt 

 to distribute the subfamily Micropteryginee between two separate 

 Orders could not be countenanced for a single moment. 



I take it, then, that Dr. Chapman would hold that the Micro- 

 pteryginee form the Order Zeugloptera, while the Eriocraniince 

 and Mnesarchceince are to remain within the Lepidoptera. 



As far as the characters considered in this Part are concerned, 

 it may be said at once that there is not a single one of them that 

 is not to be found already in some Order other than Zeugloptera. 

 The venational scheme is common to the Trichoptera and Lepi- 

 doptera; and some of its specialisations, notably the fusion of 

 1A with Cu 2 for some distance in the hind wing, are also to be 

 found in many genera of the Mecoptera and Planipennia. The 

 jugo-frenate type of wing-coupling is to be found in archaic 



