ACADEMY OF SCIENCES. 



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fornia for a distance of 165 miles in a direct line north and soutli, the boundary 

 leaving the river at Fort Yuma, Lat. 32° 43', and Fort Mojave, Lat. 35°. The 

 width of the valley within our limits is not more than ten miles, but towards 

 the mouth it spreads out into a great marshy plain and muddy estuary, bor- 

 dered on each side by desert.* The' elevation above the sea does not exceed 

 fiSO feet at Lat. 35° in the proper alluvial bottom land, which is overflowed 

 nearly every summer. The terraces bordering this belong to the Desert Region. 

 No mammals are believed to be peculiar to this valley, though some, inhabit- 

 ing the regions eastward, are supposed to extend no farther to the west. 



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MAMMALS. 



Dklelphys calif ornicus? Bexnet, Western Opossum. 



Macrotus californicus Baird, Leaf-nosed Bat. 



Lepu^ callotis Wagler, Texan Hare. 



Cervus Mexicanus 1 Gjielin, Mexican Deer. 



BIRDS. 



Polybo7-m Audiibonii Cass., 

 Craxirex Harrissii Aud., 

 Micrathene W/dtiieiji Cp., 

 Picus scaloris ? Wagl.. 

 Sp/iyrapkus nuchalis Baird, 

 Centurus uropygialis Baird, 

 Colaptes chrysoidcs jNIalh., 

 Einpidonax pusillus CouES, 

 Einpidonax obscurus Swains., 

 Empidonax Traillii ? Aud., 

 Pyroccphalm Mexicanus Sclat. 

 Helinint/iophaga Lucim Cp., 

 Pyranga Coopefi Ridgw., 

 Polioptila plumhca Baird, 

 Auriparus JIaviceps? Suxdev., 

 Psaltnparus plumbeus Baird, 

 Poospiza bilineata ? Cass., 

 Melospiza fallax Baird, 

 Pipilo Abertii Baird, 

 Cliamccpeleia passsrina Lixn., 

 Lophortyx GambelU ? Nutt., 



Audubon's Vulture Eagle. 

 •Plarris' Vulture Eagle. 

 Whitney's Dwarf Owl. 

 Ladder Woodpecker. 

 9 Red-necked Woodpecker. 

 Gila Woodpecker. 

 ]\Ialherbe's Flicker. 

 Little Flycatcher. 

 Obscure Flycatcher. 

 'I'raill's Flycatcher. 

 Red-crested Flycatcher. 

 Lucy's Warbler. 

 Cooper's Red-bird. 

 Lead-gray Gnatcatcher. 

 Yellow-headed Titmouse. 

 Lead-gray Titmouse. 

 Bridled Finch. 

 Arizona Song Sparrow. 

 Abert's Finch. 

 Ground Dove. 

 Gambel's Quail.' 



It will be observ-ed that all of these are land-birds. Others may occur 

 among the waders near the mouth of the river beyond our limits, but they have 

 never been collected or noted. The first sixteen inhabit trees, of which there 

 is a belt lining the river. The other five are more terrestrial, but never found 

 far from the shelter of shrubbery. Those marked with a ? may occur as far 

 west as the Sierra Nevada, but chiefly as stragglers, and have not been collected 



*This poi'tion resomlilcs the lower valley of (he Xile, allowing for the difierences caused by its 

 flowing south and not iwrth. 



