PHYSICAL CONDITIONS IN GENESIS OF SPECIES. 887 



from that seen in the quail, the e()k)i-s being chiefly niasseil in large 

 areas, with white markings on the wings and large white spots at 

 the ends of the outer tail feathers. In this species southern speci- 

 mens ditfer from northern ones in the black of the upper parts and 

 the chestnut of the sides being more intense, while the white markings 

 on the wings and tail are greatly reduced in area. In the northern 

 bird, four of the outer pairs of tail feathers have a large white spot 

 near the end, while in the southern form only three pairs are thus 

 marked. 



In the purple grackle the plumage (in the males) is everywhere 

 black, with, at the north, greenish or bronzy reflections ; in the south- 

 ern or Floridan form the black is more intense, and the reflections 

 are steel blue and j^urple, with iridescent bars across the middle and 

 lower parts of the back. In the northern form the female is dull 

 brownish-black, with little or no iridescence, while in the southern 

 form the female is nearly as lustrous as the northern male. The two 

 types difler so widely, not only in color, but, as previously noticed, 

 in size and in the form of the bill, that, without the connecting speci- 

 mens from intermediate localities, no ornithologist would hesitate 

 to regard them as entirely distinct species; and they were, indeed, 

 at one time so regarded. The red-wdnged blackbird has, excepting 

 its red wing patches, also a lustrous black plumage throughout, and 

 presents a similar range of variation in general color with the pre- 

 ceding; while the red of the wing patch becomes much darker at the 

 southward, and its creamy-Avhite border seen in the northern form 

 changes to yellowish-orange in the southern. 



The common blue jay, and the long-crested jays of the Rocky 

 jNIountain region, may be cited as illustrations of southw^ard increase 

 in brilliancy or intensity of coloring wdiere the prevailing tint is 

 blue; the green Mexican and Rio Grande jays of a passage from 

 yellowish-green tints into bright yellow; the yellows-throated warb- 

 lers (genus Geothlypis) , several of the flycatchers (genera Myutrehus 

 and Tjp'cnuiKs), and the meadow lark, as examples of increase in the 

 area and intensity of yellow; several of the woodpeckers (genera 

 Genturus and Sphyrapicus) ^ the cardinal finches (genus Cardinalis), 

 and some of the tanagers (genus Pyninga)^ of a similar increase 

 of red; the goldfinches (genus ('hnjxowfr'tK), and most of the species 

 above named, of increase in extent and j)urity of black areas. The 

 Rocky Mountain jays have, at the northward, a large portion of the 

 plumage rather dark ashen, which farther southward becomes bluish 

 ash, and still farther south culminates, in the Central American 

 States, in blue. In the genus Geothlyph, the Maryland yellowthroat 

 {G. fr'/clies), Avhich ranges over the whole United States, and thence 

 far southward, has at the northward the abdomen whitish ; more to 

 the southward, vellowdsh; and. in the West Indies, Mexico, and 



