266 Prof. S. F. Baird un the Distribution and 



Burgwyn, near lat. 37°, of Lagojous leucurus, Pinicola canadensis, 

 Curvirostra americana, Hesperiphona vespertina, &c., while the 

 two last-mentioned species, with Carpodacus cassini, are even 

 found in summer on the highlands about Orizaba, as shown by 

 specimens transmitted to the Smithsonian Institution by Dr. 

 Sartoi'ius. Similar intrusions of species belonging to the North 

 Mexican fauna take place up the valleys of the Colorado and 

 the Rio Grande, and of those of the eastern province westward 

 along the Missouri and along the Canadian, &c. ; but they do 

 not affect the general plan. Although characteristic of the 

 eastern province, as already stated, the Cat-bird {GaJeoscoptes 

 caru/mensis) , Red-eyed Vireo {V. olivaceous) , and Wild Pigeon 

 {Ectopistes migratoria) are found along the northern boundary 

 of the United States to the Cascade Mountains, while specimens 

 of Dendroeca coronata have even been taken at Fort Steilacoom 

 on Puget Sound. On the other hand, Turdus ncevius^ has been 

 shot on Long Island and in New Jersey, Helminthophaga celata 

 in the Atlantic states, and Zonotrichia gambeli and Spizella 

 pallida are well-known and constant visitors in the region of 

 the Great Slave Lake. 



Several species of water-birds that belong to the winter 

 fauna of the Pacific coast resort to the Slave-Lake region and 

 north of it to breed, crossing the Rocky Mountains for the 

 purpose. Among them may be mentioned Larus californicus 

 and brachyrhynchus, Colymbus pacificus, Bernicla nigricans, 

 Anser rossi, &c. This, however, may be in consequence of 

 their migrations being along a meridian line, or north and 

 south, the meridian of the westernmost point of California and 

 even of Vancouver's Island passing east of the mouth of the 

 Mackenzie River. 



In any investigation into the reasons why the eastern province 

 is of so much greater extent than the others, and exhibits such 



* I am informed by Dr. Cabot tbat a third specimen lias recently 

 (Dec. 1864) been sbot near Boston and presented to the Natural History 

 Society. As it has been met with as far east as Fort Franklin, it may 

 not improbably reach our eastern coast in company with some of our 

 eastern species bred in the Mackenzie River valley and returning' south- 

 ward to the Atlantic. 



