1 14 MORPHOLOGY, ETC., OF THH MICROPTERYGIDiE, i , 



having been placed originally in Microjrteryx, and removed to 

 Eriocrania when that genus was formed later on. Mnemonica 

 differs from Eriocrania in having R. 2 and R 3 existing as separate 

 veins in the forewing. I have marked these veins in Text-fig. 5. 

 Tt will he seen that, in this genus, Rs is not dichotomously 

 branched, but that R 3 arises from what we usually regard as the 

 common stem of R 4 and R fl . All specimens examined by me 

 show this condition, which is also the one figured by Meyrick(6. 

 p. 802), as well as by Comstock (3, p. 31 4). I fail, therefore, to 

 understand the remark of the latter author on the same page 

 that " this is an exceptional feature: usually the forking of the 

 radius is dichotomous."* From an examination of all the speci- 

 mens in my possession, representing sixteen wings belonging to 

 three species of this genus, all of which agree in this character, 

 I have very little doubt that the condition figured is the more 

 usual one for the genus. 



Further differences between Eriocrania and Mnemonica are 

 the presence of an extra distal branch of Sc in the forewing of 

 the latter, and the distal forking of R 3 in the hindwing as well 

 as the fore. There is also the complete joining-up of the distal 

 end of 3A on to 2 A in the forewing, apparently brought about 

 by a union of 3A with the cross-vein sa, and the more primitive 

 condition of vein 2A in the hindwing. Both these characters, 

 however, appear to be subject to some variation in individual 

 specimens. 



It will thus be seen that the differences between Mnemonica 

 and Eriocrania are most certainly of no higher than generic 

 value (as regards the wing-venation), and that there is nothing 

 to prevent us naming all the parts of the venation of Mnemonica 

 with certainty, now that we know the tracheation of the wings 

 of Eriocrania. The peculiar differences in the course of the 

 cubitus and anal veins in fore- and hind wings can all be made 

 out easily in Mnemonica, simply by comparing the venation with 

 that of Eriocrania. 



* So also the forking of R2+3 far distad in the hindwing, figured by 

 Comstock, would appear to he aberrant, since Meyrick states that "vein 

 10 is absent" in hindwing, and my specimens agree with this. 



