MAMMALS OF THE MEXICAN BOUNDARY, 113 



close to the ranch house of Mr. W. S. Stiirges. The onlj' water any- 

 where near is the well (Pozo Verde) of the Papago Indians, west of 

 the Pozo Verde Mountains, and a large lake (not permanent) at 

 Buenos Aj-res, 6 miles distant. Most of our specimens came from a 

 dry water course running from our camp to join the Altar River in 

 Sonora. Though there is comparatively little wood in the surround- 

 ing hills and plains, this wash was well wooded with fine hackberries, 

 mesquites, and a few oaks {Quercus emoryi and Q. ohlongifolia), 

 which latter were the last oaks seen until the Coast Range Mountains 

 of California were reached. This ravine also contained a good deal 

 of underbrush. The neighboring Pozo Verde Mountains, on the west, 

 are barren and rocky. They reach the altitude of 1,419 meters 

 (4.65G feet). Besides mesquite, there grew upon them ocotillo, 

 giant cereus, j^alo verde, and some bushes and smaller cacti. I was 

 at this station from December 9 to 10 and 11 to 28, 1893, and Mr. 

 Holzner from December 8 to 28, 1893. Large collections of verte- 

 brates were made. Few plants were obtainable at that season. A 

 molar tooth of a fossil elephant was obtained by the Papagos at the 

 Pozo Verde and presented to us by Mrs. W. S. Sturges. 



Fauna of Pajaritos Mountains. — This region was only seen by 

 us in winter, when the most interesting and characteristic animals 

 Avere hibernating and not easy to find. The reptilian fauna includes, 

 besides those mentioned as having been collected at Nogales, two 

 poisonous snakes, Elaps evryxanthas Kennicott and Crotalus tigris 

 Kennicott, and an abundance of the small box turtle {Terrapene), 

 appearing after rains. Of batrachians, a toad {Bufo) and a frog 

 {Rana vlrescens hrachycepliala Cope) were found at Warsaw Mills; 

 and at Buenos Ayres, at the beginning of the summer rains, Lieuten- 

 ant Gaillard obserA^ed "great numbers of a very large frog-like toad, 

 named Bufo alvarius by Girard. Nothing was seen or heard of them 

 until the advent of the early summer rains, which formed a large 

 shallow lake near Buenos Ayres and about 10 kilometers (6 miles) 

 north of the Jjoundary Line. These large toads then filled the air 

 with their loud cries, which increased until a deafening roar was pro- 

 duced. Numbers of them were seen hopping about, but their rarity 

 was not suspected by Lieutenant Gaillard, on which account none 

 were collected. The range of Bufo alrarins Girard, extends from 

 Monument No. 73, in Guadalupe Canyon, to the Colorado River 

 (Monument No. 205). I first met with it in a dense growth of arrow- 

 wood {Pluchea sericea) on the edge of the Colorado River at Fort 

 Mojave, Arizona, May 13, 1884. K specimen Avas carried to Peach 

 Springs and given into the charge of the hotel proprietor, who 

 allowed it to escape during my absence at the Grand Canyon of the 

 Colorado. No specimen of this toad was again seen until July 6, 



30639— No. 56—07 M 8 



