BV R. J. TILLY ARD. 089 



ginal, the Eorewing already having the apex well forward and a 

 distinct terinen, while the hindwing has its costal, subcostal and 

 radial areas much narrowed (and consequently their venation 

 much reduced), but its anal area widened. 



In connection with characters (1), (2), (7), (8) and (12), 

 together with the retention of the cross-veins ir, r-m and im, 

 and the increase in size of the anal area and its veins, note the 

 close parallelism between Stenopsychodes and its allies in the 

 Trichoptera (p. 629), and that of the Archetype of the Hetero- 

 neura in the Lepidoptera. If the family Polycentropidae had 

 continued this line of evolution, by reducing the subcosta and 

 radios of the hindwing, there would have resulted a group of 

 Caddis-ilies closely comparable with the Heteroneura amongst 

 the Lepidoptera. 



The "percentage archaism" of the Archetype of the Hetero- 

 neura, as compared with that of the Order, if worked out on 

 the twenty characters given in Table iii. on p. 650, will be found 

 to be 52.5, i.e. less than that of the Micro pt eryg ia hie, Eno- 

 craniidae and Hepialidae, as might have been expected. But a 

 fairer comparison would be obtained by adding to this Table 

 al-o those characters given in Table iv. on p. 690 in which the 

 Heteroneura are specialised, but which are not included in Table 

 iii., since they do not come into question in the case of the 

 Homoneura. By this method, a pei'centage archaism of 4-1.4, 

 out of a total of twenty-seven characters, will be obtained; and 

 this percentage, I think, very fairly represents the correct posi- 

 tion of the Archetype of the Heteroneura in the evolution of the 

 Order. 



By multiplying the percentages obtained in Table' iv. by the 

 factor 0.444, we can obtain a comparison of the "percentage 

 archaisms" of the various groups of Heteroneura, when the 

 percentage for the Archetype of the Order, and hence of the 

 Homoneura also, is given as 100. To make this comparison 

 fair for the Homoneura also, we must add to the twenty charac- 

 ters given in Table iii. the seven characters in which the Arche- 

 type of the Heteroneura is specialised, and in which, therefore, 

 all the Homoneura must be credited with an extra seven "A's " 

 The combined results will then be as follows: — 



Micropterygidae 79.5, Eriocraniidae 72.2, Hepialidae 70.3, 

 Prototheoridae 53.7, Cossidae 41.7. Mnesarchaeidae 38.9. Tineina 

 33.3, Castniidae 30.7, Tortricina 27.8, Psychina 22.2, Pyralidina 

 18.2 and Rhopalocera 15.3. 



