1892.] Elliot, Inheritance of AcquircJ Characters. S^C 



the island may be due to the tact that Sa/p/i/ctes, being a genus 

 whose members are feeble in Hight, required a greater develop- 

 ment of wing and sternum to place it on a par with other species 

 whose wing power was naturally sufficient to successfully combat 

 the influences of insular life, and which Salpinctes alone lacked. 

 But to draw my illustrations solely from island forms, may be 

 objected to on the ground that the influences there exerted are 

 more powerful and exceptional than in other geographical areas 

 which have environments not so abruptly separated. I will 

 therefore cite the effects we assume continental environments 

 have upon a form of wide distribution, and take for my illus- 

 tration the familiar species JSIelospiza fasciata Gmel. and its 

 allies. This species and its subspecies are distributed throughout 

 North America from the Atlantic to the Pacific, and from Mex- 

 ico to Alaska, and its islands. The type is found in the form 

 inhabiting the eastern States, and extends its range to Nebraska 

 and Indian Territory, and is generally constant in its charac- 

 ters, the variations being scai'cely noticeable, as would be ex- 

 pected from the similarity of the environment throughout this 

 dispersion. New Mexico and Arizona present a form, M. f. fal- 

 lax, that varies from the type in its extreme pale coloration and 

 increase of size. This region possesses climatic Influences of an 

 arid chai'acter, very different from that with which the type 

 has to contend, and in certain portions of the habitat, as in the 

 region of the Gila River, these influences cause individuals to ex- 

 hibit markedly different characters from those observed In the 

 type. In Colorado, Utah, Nevada and northward occurs another 

 form, M. f. moniana, ^vh'ich In winter visits the neighborhood of 

 Tucson in Arizona. This is darker In color than ya/Za.r, as might 

 be supposed it would be from the greater humidity of Its habitat, 

 but the two forms seem to run Into one another on the northern 

 and southern limits, respectively, of their dispersion, and indi- 

 viduals thus intermediate present characters that are Inconstant, 

 and which are probably the result of interbreeding. The foot- 

 hills of the Sierras, through the mountains, and in their western 

 foot-hills, produce another departure from the type, M.J". heer- 

 manni^ and here we have a form of a much darker shade of 

 brown, and bill intermediate In size between those of the two 

 forms first mentioned. In the neighborhood of Comondu, in 

 Lower California, the physical conditions have differentiated 



