April 1895] 



rsruiE. 



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character lacking, we may most reason- 

 ably interpret the Incident on its merits, 

 and not in the manner of the people 

 who seek after a sign. The occurrence 

 will simply be an extremely unusual 

 fact, contrasting with an almost uni- 

 versal occurrence of the directiv 

 contrary fact. 



Colias lias few species for so domi- 

 nant a genus, a wide range (jf variation 

 being retained within the limits of a 

 species. Consequently, species which 

 are closely allied contrast very unequally 

 in dissimilar comparisons, a great or a 

 small contrast resulting according as 

 typical or approximate specimens are 

 compared. Hence it is, the species 

 differ somewhat vaguely, so th.it super- 

 ficial students are easily convinced tliat 

 we have far too m.m\' species of Colias. 

 The general unity of pattern-method 

 throughout the genus, combined with 

 the wide species-content .is to \ariation, 

 causes a profuse diversity within the 

 species, accompanietl sometimes by an 

 almost bewildering resemblance be- 

 tween one species and another. Even 

 species not adjoining may show an 

 approximation sufficient to render ditii- 

 cult an estimate of their degree of 

 alliance. In the case under consider- 

 ation this applies. It appears to mo 

 somewhat probable that the approxi- 

 mation between Hecla and Meadii 

 may be merely an extreme instance of 

 v.'hat for want of a better term I will 

 call tliffusive resemblance, and not in 

 reality a result of contiguous alliance. 

 Until the larva of Hccla is known we 

 cannot be quite certain of the degree 



of relationship existing between Hccla 

 and its two Rocky Mountain allies. 

 It is easilv known to be a ditlerent 

 species from the other two. The view 

 that the three species are directly 

 related, although liighly plausible on 

 geographical grounds, is preliminary 

 rather than tinal. It is not especially 

 impri)b;ible tliut the closer alliance 

 of J-Iecla is with Chrysotlteme and 

 T/iisoa. The larva of Elis is greatly 

 similar to that of the untypical form 

 of Colias i/astes which occurs in tlie 

 Bow Valley aliove timber. The dis- 

 tinction between them is that Nastes 

 is smaller, darker, and apparently far 

 mole primitive than Elis. The imagos 

 indicate still more plainly the linear 

 gap Iietween the two species. The 

 larva of Hccla is a desidei'atum, to 

 assist in determining whether that 

 species is more closely allied to Chry- 

 sotheme or is one of the intermediate 

 terms between the early stock of A^astes 

 and the modern forms A/eadii and Elis. 

 In Proceedings of the Acad, of Nat. 

 .Sciences of Philadelphia, page 156, 

 1S92, Dr. Skinner describes " Colias 

 hecla pallida N. var. 9 >" from a 

 single instance, and a figure of this 

 examjjle is published in Entomological 

 News, Vol. 3, plate 2. Both the 

 description and the ligiu'e suggest 

 Nastes rather than Hccla. The fig- 

 ure indeed admirably represents the 

 form of Nastes female which is found 

 on the mountains about Laggan, larger 

 than the Labrador type, and nearer to 

 the form Wcrdandi of northern 

 Europe. I make this note hoj^ing it 



