4 Zoologia: N. Y. Zoological Society. [Vol. 1 



Speaking of the climatic or geographic variation mentioned 

 above, Dr. J. A. Allen says: — "Secondly, and coincidently with 

 the decrease in size southward, is a change in coloration, which 

 may be described in general terms as a restriction in area of all 

 white markings and a corresponding increase in the area of the 

 dark markings, together with, generally speaking, an increase in 

 the intensity of color in markings or areas of other tints than 

 black or white, as yellows, greens, browns, etc., and also in iri- 

 descence, in birds of metallic tints. * * * 



"It is equally well known that in continently dispersed 

 groups, pallid tints accompany desert areas and arid conditions 

 of climate, and that increase in depth of color, particularly in 

 gray, brown and olive tints, is an inseparable accompaniment of 

 regions of heavy rainfall and a moist climate, so familiarly illus- 

 trated in the northwest coast region of North America. * * * 

 In other words, regional areas of peculiar climatic conditions im- 

 press upon their animal inhabitants a certain distinctive phase of 

 coloration, developing in some instances wholly new specific 

 types, in others merely forms that intergrade with others of the 

 immediately adjoining districts." 



Near the end of the same article we read that Dr. Allen be- 

 lieves that the evolution of species and races has been brought 

 about chiefly by environment, as opposed to natural selection — 

 used in the original restricted sense — and that the main factor 

 in this evolution is climate. 



Two months later in a second article Dr. Allen thus argues 

 for the inheritance of local differences in color of subspecific 

 value : 



"Young mammals in the nursling stage have a pelage differ- 

 ent in color and texture from that later acquired; young birds 

 have a characteristic nestling plumage different in color and 

 texture from that of the adults, or from that acquired with the 

 first moult. Every experienced mammalogist and ornithologist 

 knows that the local differentiation in color between the sub- 

 specific forms of a group is often — but not always — much more 

 strongly expressed in the first pelage or plumage of the young 

 than in the adults of the same forms. In view of such facts it 

 seemingly goes without saying that local differentiations are 

 transmitted from parent to young, and are hereditary in the usual 

 sense of that term; doubtless no one questions their continued 

 transmission from generation to generation so long as the en- 

 vironment remains stable. Probably also few would question 

 that were representatives of a strongly marked local form — 

 in the case of birds, either as eggs or mature birds — to be trans- 



