JESimpson, 1938. 650+ ft, 11.3 mi. w. Hermosillo, Sonora. April 30, 1938, continued. Made camp off the road and set 50 mousstraps and 50 live-traps on tan, sandy soil sparesly covered with dry grass among palo verde (many in seed), mes- quite & palo fierro trees (dominantly) with some pitayo, cholla, and bara blanca. May 1, 1938. Caught 12 Perognathus penicillatus (3 in live- traps turned loose; put up 0 -> 263-67; cheek-pouch contents saved), three 0 -> Dipodomys merriami (cheek- pouch contents saved), 2 Onychomys torridus (0 -> 267 and ♀ 268; 0 -> 267 moultng), and 3 Reithrodontomys sp. (0 -> 260 and ♀ no. emb: 261, 262) species not known.) The surplus rat were thrown just beyond camp; we watched ravens and cara-caras fight over them; three Audobon's cara-caras first arrived, and fought among themselves. The cara-caras held the rats in their feet and tore at them with the beak, but the ravens each ^spiked one with the bill and flew away to eat. Broke camp and drove toward Rancho Libertad but missed the road and arrived at our proposed second camp after Rancho Libertad at a: 270+ ft., Ranchode Costa Rica, Rio Sonora, Sonora. Here we were cordially welcomed by the ranch-owner, Jim Bliven, an American who has (5,000 hectares) managed this 12,360 A acre-ranch for 30 years.