110 MORPHOLOGY, ETC., OF THE MICROPTERYGIDiE, i., 



dichotomies of R and M, and the somewhat greater reduction of 

 the anal area. R u is, of course, absent in Hepia/idce, and R24-3 

 is always forked near the apex. 



Text-fig. 1 shows also the venation of the imaginal forewing of 

 Eriocrania, for comparison with the pupal tracheation. It will 

 be seen that the serial vein formed from M, pa and Cuj is by no 

 means straight, as it is in some higher types, and there is little 

 difficult}' in recognising the parts that go to its composition. 

 The only other specialisations are (a) the distal union of 2A 

 with 1 A to form the forked anal vein (note that trachea 2 A does 

 not meet 1A); and (b) a great weakening of portions of the 

 imaginal venation, giving rise to three hyaline areas, within 

 which the main veins and cross-veins alike are obliterated. These 

 areas are known as ihyridia, and are also to be found in Tricho- 

 ptera, Mecoptera, and Planipennia. In Text-fig 1, I have indi- 

 cated the courses of the veins on the thyridia by dotted lines; 

 one of them covers the median fork, another runs from R 4 _, 5 to 

 the dichotomy of M 1+2 , and a third covers the distal end of Cu 2 . 

 The only true cross-veins present in the forewing of Eriocrania 

 are the humeral (hm), the radio-median (r-m), the medio-cubital 

 (m-cu), the posterior arculus(pa), the cubito-anal (cu-a), and the 

 subanal (sa). It should be noted that the basal piece of Cuj has 

 frequently been mistaken for the cubito anal cross-vein, as by 

 Forbes*(4), while the misapprehension as to the real identity of 

 1A has led to an incorrect naming of the true cubito-anal itself. 



'» 



The Hind wing. (Plate iii., fig.l, Text-tigs. 3-4). 

 The tracheation of the hindwing of the pupa, though on the 

 whole resembling that of the forewing, differs from it in at least 

 two very important points. Firstly, the cubital fork lies much 

 closer to the base of the wing; and, secondly, there is a very 

 important specialisation in the course of 1 A, this trachea coming 

 to lie alongside Cu 2 for a considerable distance, as may be seen 

 in Text-figs. 3-4. Consequent upon the changed position of the 

 cubital fork, the posterior arculus (pa) is shorter and much less 



* The wing figured by Forbes is actually that of Micr&pteryx ( Erio- 

 cephalaj thunbergetta, 



