134 ANIMAL LIFE IN THE YO SEMITE 



Our first specimen of the Mountain Lemming Mouse was captured at 

 an altitude of about 9750 feet in the head of Lyell Canon on July 20, 1915. 

 Mr. Charles L. Camp of our party had spent much time examining clumps 

 of Sierran heather (Bryanthus hreweri) for evidence of the rodent and 

 had set several lines of traps in likely looking situations. This individual 

 ■was taken in a trap set beside a log at a small hole out of which fresh earth 

 had recently been pushed. On the top of a nearby rock and beneath some 

 brush was a mouse nest with a hole at the side, and a trap set there had 

 been sprung two nights previously. About 50 feet distant from the hole, 

 and in a patch of heather, a pile of old droppings about 6 inches in diameter 

 lay on the ground as if they had been deposited in a cavity beneath the 

 previous winter's snow. The general situation was in an open stand of 

 lodgepole pines at a level place dotted with clumps of heather. A rocky 

 cliff stood to one side, and a stream ran by about a hundred yards distant. 



At higher altitudes in Lyell Caiion, even up to 10,700 feet, masses of 

 black and greenish droppings were found which, because of their similarity 

 to the dung-masses of a species of Phenacomys in the coast region of Cali- 

 fornia, were believed to be those of orophilus. Possibly the animals had 

 wintered here beneath the shelter of down logs or rocks. Also in various 

 situations, usually associated with the droppings, there were found 

 numerous cuttings of heather and other plants, these cuttings being IV2 

 to 3 inches in length. In one instance willow cuttings of the same nature 

 were observed. 



The four specimens of Mountain Lemming Mouse captured include 2 

 adult males, 1 female, and 1 male, sub-adult. In general appearance they 

 remind one of meadow mice (see fig. 20c), to which they are certainly not 

 distantly related. The short tail and pale gray coloration are the chief 

 external features of difference. Obviously the population of this mouse 

 is far below that of even the Cantankerous Meadow Mouse, else more would 

 have stumbled into the many traps set in places similar to those in which 

 our four specimens were taken. 



Pocket Gophers. Genus Thomomys^^ 



Field characters. — Size near that of House Eat, but form stout, tail short, ears and 

 eyes very small (pis. 27, 29) ; length of body six inches or less; tail less than half length 

 of body, scantily haired, bare at tip; a fur-lined cheek pouch opening outside of mouth 

 on each side; cutting teeth (incisors) project conspicuously beyond lips which never 

 cover them; forefoot not spade-like but provided with long slender claws (fig. 5b), longer 



11 The Pocket Gophers of the Yosemite section are representative of five distinct 

 kinds, as enumerated below. Although two of these, pascalis and viewa, are indicated as 

 subspecies of one species, bottae (upon the basis of conditions farther northward in 

 California), actual intergradation between any two of them was not found by us to 

 take place within the region studied; ail the five forms in the Yosemite section behave 

 toward one another as full species ; no two were found living in exactly the same locality. 

 The geographic habitat of each is distinct (fig. 24). 



