1936] MAMMALS OF OREGON 179 



twitching, until he could pounce upon it. If he got a good hold, the 

 struggle was short, and the mouse quickly dropped, limp and help- 

 less, as his long sharp lower incisors penetrated its brain near one 

 ear. If the mouse was of his own size and caught by the back end, 

 there was a rough-and-tumble mix-up. The victim might be allowed 

 to escape in order that a better hold might be obtained next time, but 

 the pursuer was persistent and only awaited his chance. White- 

 footed and meadow mice of his own size were regularly killed and 

 eaten. In one case a white-footed mouse was not killed, and two 

 mornings later it was sleeping with him in a better nest than he 

 usually made for himself. For a couple of weeks he lived with the 

 white-footed mouse on friendly terms, possibly waiting for a scarcity 

 of food, or he may have been lonesome or cold, or needed a good nest 

 builder as assistant. The white-footed mouse was then returned to 

 his home in the sagebrush, and Owjchamrys accompanied his captors 

 on a long journey. 



In Arizona he was given the company of four individuals of the 

 smaller species (Onychomys tomdus) of his own genus, and from 

 the first all were friendly and slept together in one nest. In dispo- 

 sitions they seemed surprisingly friendly and peaceful, in striking 

 contrast to some of the gentler and more timid rodents. 



Ony had a, strong musky odor that was probably the result of a 

 diet composed largely of insects and meat, though it did not vary 

 noticeably with different foods. His house at first became very rank 

 if not kept well cleaned out and sanded, but later when given a sand 

 box for a toilet he used it exclusively and kept his house neat and 

 clean. His fur would become mussy and rough when he did not 

 have plenty of clean sand to roll in, but after a sand bath it was 

 clean and fluffy. He did not usually make a good nest, but just 

 pulled anything warm up around him when it was cold and sat on 

 top of the nest material when the weather was warm. 



His common everyday voice was a series of rapid, short, sharp 

 squeaks, each, each, each, or chip, chip, chip, just what a little dog of 

 his size would do in the way of barking, and it was used in the same 

 way as a protest when annoyed, angry, or cornered. 



His call note was a fine, shrill, prolonged whistle, insectlike in 

 quality, but so thin that only keen human ears could detect it. It 

 was heard only at night, most commonly in the spring but occasion- 

 ally through the summer. It may be a sex or mating call and also a 

 hunting call or recognition signal. The writer had occasionally 

 heard it at night in the sagebrush country, but not until he had kept 

 the animals in captivity did he learn its source. In Arizona, early in 

 the spring of 1921, with no companions of his own species, Ony 

 was evidently lonesome, and every evening when he first came out 

 of his nest would sit on top of his nest box, lift his nose in the air, 

 and with wide-open mouth send out his call. The howl of a wolf 

 of his size would not be very different and the manner of giving 

 it would be identical. The call was repeated several times each 

 evening until he gave up the hope of calling a mate. At home in 

 Washington, where he was kept in the library all winter, the call 

 was not heard until the springlike days of February set the other 

 animals to breeding while he, alone, was evidently calling for a mate. 



At night he was active and energetic, darting about his cage or 

 running at top speed on his revolving disk by the hour. In cold 



