218 [31 ARCH 



Palpi, differ from the male, in being tinged with rose color, upon the 

 third joint. 



Hah. — Rocky Mountains, Colorado Territory. (In my collection, S , 

 and that of the Entomological Society. 9 •) 



This species was collected in August, 1864, by Mr. James Ridings, 

 and considered as specimens of Coliax Alexandra, from which, how- 

 ever, they differ considerably 



The wings in both sexes are more obovate, — more rounded at the 

 angles, — than in the corresponding sexes of Alexandra, especially the 

 inferior wings. 



Besides the differences of the female, it may be readily distinguished 

 from Philodice, by the total absence of the sub-marginal ferruginous 

 spots on the under side, which though frequently more or less obsolete. 

 I have never seen entirely wanting. 



Colias philodice. Godart. 



I have found very few members of this family to possess 'a greater 

 variability in size and ornation, than this very common and abundant 

 little species. Almost every locality possesses some trait peculiar to 

 itself, and distinctive from any other, appertaining to another place of 

 collection. Some of these differences are very minute and can only be 

 distinguished when brought into comparison with a large series; others, 

 again, vary so much as to apparently form distinct species, when con- 

 sidered alone, but when compared as before, they unite with the typical 

 form by such insensible gradations, that it is impossible, at present, to 

 consider them other than varieties : — ultimately, there can be no doubt, 

 they will break loose from the parent stem, by a still greater range of 

 variation, and consequent diminution of connecting links, and thus, as 

 nearly all allied species have originated, assume a definite position in 

 the constantly increasing number of species. 



It is indeed a matter of some difficulty to determine which is the 

 true form of the insect, and which, its abnormal conditions. Authors' 

 description, are most generally sufficiently accurate, by which to ensure 

 its determination, but none of them have presented any, save one, the 

 white 9 > °f the numberless shades of variation, incidental to locality, 

 climatal influence, and perhaps other causes, of which we are ignorant. 



The variations may be divided into those of size, and ornamentation. 



In regard to size, I have specimens varying from 1.75 — 2.66 inches; 

 and I have noticed, that very generally, there is a tendency to increased 

 size in the South and West. 



The females are usually the largest, though I have caught males in 

 the western parts of Pennsylvania and New York, fully equalling in 



