BY R. .J. TILLYARD. 97 



of set specimens, of cleared mounts of the wings and of the 

 mouth-parts. The same is true of those larval and pupal forms 

 known. Thanks to the labours of Dr. Chapman, the complete 

 life-history of the genus Eriocrania is known; while, in the 

 genus Micropieryx, the same indefatigable worker has succeeded 

 several times in rearing the insect from the etjil as far as the 

 last larval instar, though, so far, baffled in obtaining the pupa. 

 The larva and pupa of the genus Mnemonica are known; they 

 are closely related to those of Eriocrania. 



The differences between the larva of Micropteryx, on the one 

 hand, and those of Eriocrania and Mnemonica on the other, are 

 so great as almost to justify in themselves Dr. Chapman's 

 original separation of the family Micropterygidce (sens, lat.) into 

 the two families Micropterygidce (s.str.) and Eriocraniidce(l). If 

 we take into account also the differences in the mouth-parts of 

 the imagines, this separation is surely justified entirely. Never- 

 theless, in entering upon the discussion with which this paper has 

 to deal, I have felt it advisable to follow Meyrick in treating 

 these insects as a single group, provisionally taken as of family 

 rank, merely for convenience of title, and for facilitating the dis- 

 cussion itself. Whether they belong to one family or two, to one 

 Order or two, or to what Order they are to be relegated, it is the 

 purpose of this paper to try to discover. Hence, in the title, I 

 speak of them simply as the Micropterygidce (sens, lat.), without 

 prejudicing the case by indicating that this group belongs to any 

 definite Order of Insects. 



The receipt of Dr. Chapman's paper i2), and my own discoveries, 

 so stimulated my interest in this group that I proceeded to get 

 into touch with Dr. Chapman himself by correspondence, and 

 asked him whether he could assist me to carry out a full biolo- 

 gical study of it. Less than a year has passed since this cor- 

 respondence, already so fruitful of results for me, was inaugu- 

 rated; and I find it hard to realise that the fine collection of 

 material now in my hands is the result of so short a period of 

 contact with Dr. Chapman's wonderful generosity and kindness. 

 I feel that no words of thanks of mine can possibly convey to him 

 my deep appreciation of what he has done; nevertheless, I here 



