456 R. Ridgway— Relation between Color and 
crown deep black. Sayornis nigricans,* from California and 
orthern Mexico, has the crissum pure white; Mirador speci- 
tropical American examples (var. saaheh Costa Rica and 
Ecuador), have it dark snuff-brown, while examples from Mira- 
dor, Mexico, are as exactly intermediate in colors as they are in 
itat. 
The same law as s regards the Pacific province of North Amer- 
ica is made evident by the well known cases of Picus villosus 
var. Harrisii,t P. pubescens var. — wl Sphyropicus varus 
var. ruber,f the Northwest coast forms of Falco peregrinus, F. 
Columbarius, Bubo plat ates Scops ai and numerous other 
similarly affected species 
IL The law affecting the primary colors,—Of this class we may 
begin with yellow, as being the color whose changes are most 
nearly parallel with those of black, i. e., affected nearly simi- 
larly in middle America and the ‘Pacific province of North 
America. The following cases afford illustrations:—Xan- 
thoura luxcuosa** from the Rio Grande of Texas and Northern 
Mexico, has the lower Sale deep green, while the same species 
from Guatemala (var. Guatemalensis),++ is pure gamboge yellow 
* SAYORNIS NIGRICANS, 
nigricans Swains., Phil. Mag., 1827, —Sayornis n. Bonap.. 
Compt. Hager 657. “Baird, Be N.A., 1858, 183.5 Sel., Cat, "1862, 200. 
Hab, California and Northern — 
+ SAYORNIS NIGRICANS a AQUA’ 
is aquaticus Scl. and Salv., This, cose A aennscra 
Hab. Central pay from Southern Mexi 
} Picus vILLosus var. HARRISII. 
Picus Hinwviantt hit, Orn. Biog., v, 1839, 191, pl. 417.—Baird, B. N. Am. 
1858, 87. 
ab. Western Province of N. Am., and south into a where it grades 
into the smaller and still darker var. Jardini, which reaches its extreme 
evn goa eon in —— — 
| Prous pus 
Picus Gairdnert hak: eee Bice, ie 1839, 317,—Baird., B. N. Am., 1858, 91. 
Hab. Western Province. sp 
bf 5 Swat omy VARIUS V: 
rec ruber Gmel., 8. N, i 1788, 429.—Sphyropicus ruber Baird, B. N. A+ 
Hab. Pacific Province of N. — 
** XANTHOURA LUXUOSA var. Li 
- Garrulus luauosus Lees., R. Z., Z., April, 1839, 100. Xanthowra 1. Bonap., ConsP- 
1850, cron oe B. x. Am., 1858, 589. 
. Mexico, from the Rio Grande to Isth. Tehuantepec. 
GUATEMALENSIS. 
