Peterson 1935. 150 mouse traps set out on dry gravelly slopes ½ E of Marys River, 22 mi. N of Beeth, Nevada. July 6. Catch included 20 Peromyscus m. sonoriensis, 4 Microdipodops m. megacephalus, 2 Lagurus c. intermedius, 4 Perognathus p. sliiaceus, 4 Eutamias m. scrutator and 1 Orsoscopes montanus. Total = 34 mammals and 1 bird. Skins prepared of 1 Eutamias m. scrutator, 2 Lagurus c. intermedius, 3 Perognathus p. olivaceus, and 1 Peromyscus m. sonoriensis. Dr. Hall prepared the 4 Microdipodops m. megacephalus. Expedition above Buena Vista Ranch on Marps River by Dr. Hall, Mr. Russell, Mr. Richardson, + myself to investigate presence of beaver. Evidence of beaver workings in several places noted. 6 beaver traps set. Porcupine shot by Mr. Russell; night hawk shot by me. Veined Dr. Hall's Ford in grass-grown ditch: out without much trouble. July 7. Catch included one 46½ lb. beaver and one little beaver of the season weighing approximately 8 lbs. Porcupine, shot by Mr. Russell, skinned by me, skin salted + rolled up. Both porcupine (Erethizon) and beavers (Castor) examined for internal parasites. Former found & harbor 2 Cestodes in upper portion of small intestine, and samples of intestinal and fecal,