THE CANADIAN ENTOMOLOGIST. 175 



wings. The greater the extent of absorption of 11. by III. (the radius), from 

 the base of the secondaries outwardly, the more speciaHzed is the form. 

 In the Limenitini {Nymplialince) the absorption is carried forward to the 

 point of issue of the rudiment of I., so that the subfamily Nymphalince 

 may apparently be separated from the Argynnince by this character. 

 While I have in various places in my paper correctly stated the change in 

 the position of II. and III., owing to this basal fusion of the two veins, 

 I have in others written of a withdrawal of I. towards the point of 

 junction of II. and III., which, in fact, is the reverse of what takes place, 

 although the effect seems the same. I. probably remains constant, or 

 nearly so ; in the cases where it is reduced to a mere scar it seems still 

 to occupy the same relative position on vein II. It is extinguished by 

 absorption. At the same time the fusion of II. and III. constantly 

 changes in extent. In low forms, such as Leptidia, the two veins seem 

 wholly separate at the base of the wing. In Argytmis, which is the 

 lowest Nymphalid I have examined, the fusion at base is very limited, 

 whereas in the highest Nymphalids the fusion is carried up to the point 

 of issuance of I. In the Pierids the fusion is generally limited, and 

 here, as I have pointed out in my essay, they lag behind the Nymphalids. 

 The extent of the absorption is everywhere the measure of the special- 

 ization. 



The last point to which I would here draw attention is the junction 

 of the cross vein on hind wings with IV3, or rather V^ Here the 

 Pierids have again lagged behind, the cross vein reaching IV3, although 

 the portion of the base of IV3, between the junction of the cross vein 

 and Vi, must be held to belong to the cross vein. In the Parargince 

 and Nymphalidce the cross vein is withdrawn to the point of issuance 

 of Vj. The lower Meadow Browns agree with the Linmadidce and 

 Pieridce in the position of the cross vein of secondaries. In the 

 Riodinidce (I have ohly examined the type) the cross vein is specialized 

 as in the Nymphalids, while it is slightly removed outwards in the 

 Theclince and Lyccenince. Where the cross vein fails to meet the point of 

 issuance of vein Vj, lying outside of it, we must describe IV;) as issuing 

 from the cross vein, to which the base of IV3 morphologically belongs. 



A study of both fore and hind wings shows that on both the same pro- 

 cesses are repeated, but the initial impetus for the changes seems to be 

 always given by the hind wings. It is as if a wave passed over the 

 wings, coming from tne hind pair and breaking over the primaries, 

 carrying these frail creatures further along their airy paths into their 

 unknown future. 



