COLIAS IV. 



State. Tu the highlands this Colias is restricted in the number of its annual 

 broods, and tlie form Eurylheme is either unknown, or very rare, according to 

 the locality, the species Ijcing mainly represented by Kcewa>/dbi. And at cer- 

 tain levels throughout the State the upland races come in contact with the low- 

 land, — the digoneutic, practically limited to a single form, meeting the poly- 

 goneutic and polymorphic race ; and by the consequent cross-breeding the 

 thorough separation of the lowlanders into seasonally distinct forms is inter- 

 rupted and can never become so definite as on the vast plains which occupy 

 Texas, and the regions to the immediate north and south of it. (See Note.) 



IV. In Texas and the regions adjoining there are no inequalities of sui'face 

 snfiicient to affect the general result, and this species has for ages been subject 

 to the most favorable climatic and geographic conditions for the development of 

 polymorphism. There are lour annual broods, the earliest, flying from November 

 to February, consisting of Ariadne, the next of Keeicaydin, the third of an inter- 

 grade, and the last of Eurytheme, the separation being marked. If either form 

 appears in any degree out of its season, it is not in sufficient numbers to invali- 

 date the rule. The species here is truly polymorphic and seasonally so. 



Keeicai/din, throughout the range of the species, is the most constant of the 

 three forms,"and I should consider it the winter form and therefore tiie primitive. 

 But where tlie species is polygon eutic, a second winter form, Ariadne, has arisen, 

 and in some districts where it is di- or tri-goneutic, an intermediate variety, 

 strongly tending towards this second winter form, sometimes manifests itself. 

 The case is much as in Papilio Ajax, which has one summer form 3Iarcclhcs, l)ut 

 two winter forms, Tclamonidca and Wal>ihii, the first the primary, the other sec- 

 ondary. Application of cold to chrysalids of any of the forms of Ajax causes 

 Telamonides to appear, and similar experiments made with chrysalids of this 

 Colias will be apt to show which is the original winter form. 



The resemblance between Eunjtlieme and Philodice I have spoken of, and 

 probably every variet}' and sub-variety of each form of the first of these species 

 can be paralleled in the other, color alone excepted. The variety of Philodice 

 shown on Plate III., of Colias, Figs. 2, 3, corresponds with Ariadne; Figs. 1, 2, 

 Plate II., correspond with the typical Eurytheme. Even the appearance of the 

 dog's head, characteristic of Colias Ccesonia, and not unfrequently to be seen in 

 the female of Eurytheme, occasionalh^ appears in Philodice. Albinic females ajj- 

 pear in every brood as in Philodice. In that species these females are as com- 

 mon in the eai'ly spring brood as in any of the later ones, although the contrary 

 has been stated by authors ; and judging from the number of albinos received 

 by me from many quarters, the same is true of Eurytheme. 



The larvce of Eurytheme and Philodice are scarcely, if at all, distinguishable 



