264 Prof. S. F. Baird on the Disbibution and 



the mountains opposite San Diego explains the appearance at 

 that point on the coast of a few species Hke TyrannuR vociferans, 

 Sialia ardica, Polioptila melanura, &c., so characteristic of the 

 middle province. The southern boundary of this province 

 during the summer may be considered as occupying the valleys 

 of the Rio Grande and Gila ; but along this line it is greatly 

 mixed up with the peculiar fauna of Northern Mexico^ which, as 

 far as its summer birds indicate, is almost entitled to be con- 

 sidered as a fourth main province. 



The eastern province to the north merges into the Arctic, and 

 southward exhibits a very important subdivision in the hot 

 region of the South Atlantic and Gulf States, which is bounded 

 to the north by the isothermal of 80°, extending, however, up the 

 coast to the Dismal Swamp of Vii'ginia, or even to the James 

 River. To the west it ranges along the isothermal of 83° or 85°, 

 following the line to the N.N.W. along the valleys of the 

 Rrazos, Red River, the Washita and the Canadian. Most of the 

 species belonging to this subdivision reach along the valley of 

 the Mississippi to a point far north of their limit on the Atlantic 

 slope, the Swallow-tailed Hawk, Parrakeet, and other charac- 

 teristic species being well-known visitors to Cairo, St. Louis, 

 and even as far north as Wisconsin. This subdivision of the 

 eastern province experiences a still further modification in the 

 southern part of Florida, in consequence of the proximity of the 

 Bahamas and Cuba, which causes stragglers of the West Indian 

 fauna to enter its limits, especially along the south-eastern 

 keys. Some of these are Certhiola bahamensis, Progne cryp- 

 toleuca ?, Vireo barbatula, Quiscalus aglceus (Q. baritus, Baird, 

 B. N. A. p. 556), &c. The only really peculiar indigenous 

 land bird in Florida is the Florida Jay [Cyanocitta floridana), 

 seldom, if ever, found out of that State. As far as is known, 

 there is no corresponding southern subdivision on the west 

 coast in the western province, although California and Wash- 

 ington Territory have each some peculiar species. 



As in the eastern province, so in the middle, there is a sub- 

 division along the southern border inhabited by species belong- 

 ing more particularly to northern Mexico, and occupying the 

 valleys of the Rio Grande and Gila, extending northward along 



