16S 



THE CANADIAN ENTOMOLOGIST. 



Fig. i8 



Fig. iQ. 



butterflies is that of Aporia which runs as 

 shewn in Fig. i8. 



Pieris is also a very simple type of neur- 

 ation (vide aiite, p. 47, Fig. 2) where 9 is 

 1^ absent and a nervure, which I prefer to call 

 f^ 8a, takes its place at apex. 



The next step forward is to Euchloe 

 (ante, p. 47, Fig. 3), where nervure 8a of 

 Pieris and 9 of Aporia are both developed. 

 This is followed by the neuration of belia {vide Fig. 17), above, where 6, 

 7, 8, 8a, 9 and 10 all come from one stalk, 11 only 

 coming from the top of the cell. The highest point 

 of development in this direction is reached in 

 Leticophasia, Fig. 19. 



I have also examined the exotic species, Delias' 

 eucharis, which comes nearest to Aporia (Fig. i8)» 

 but lacks 10; and Teracolus dance, which comes very 

 near Aporia, 7 coming, however, from apex of cell with 8. 



It is very evident that there is plenty to do in these groups before we 

 can suppose we know anything about their real relationships, and that 

 even in the light of our present knowledge our generic anangement is 

 sadly at fault. I can only hope that these off-hand observations made 

 on a few species, when working for other results, may lead to some 

 arrangement that does not upset the primary structural characters we 

 everywhere meet. 



It may be here not out of place to say why I prefer my own system 

 of numbering the nervures. A completely typical butterfly may be said 

 to possess 13 nervures (on forewing) ending on the margin of the wing. 

 Of these, all are rarely (probably never) present, but those that are must 

 have their representatives in the typical butterfly. No. i, which ends at 

 anal angle, is always present. If, now, we look at a Papilio, we see 2, 3 

 and 4 coming from the base of the cell, 5 from its lower external point. 

 Now, I maintain that this last nervure, which is really a continuation of 

 the lower edge of the discoidal cell, should always be called by the same 

 number; hence, if we call it 5 in Papilio, we sliould call it 5 in every other 

 butterfly, since it is structurally identical in all. Now, if we simply 

 number upwards, as is done by Mr. Dyar (p. 100), we should call this 

 nervure 4 in Pieris, because only two come from bottom of cell (3 being 



