372 University of California Publications in Zoology [Vol. 12 



on either side, but chiefly on the water side. Two holes in the ceil- 

 ing, from the neighborhood of which dirt had been scratched into 

 a pile, exposed a passage way about fourteen inches in diameter. 

 It was damp, but there was no running water in it, as was the 

 case a few feet farther down in the tunnel. The fresh sign con- 

 sisted in the trampled appearance of the exits, fresh cuttings of 

 grass in them, and the broken leaves of plants at the entrance. 

 Another runway was found with a passage leading up to a large 

 hollow under a rock, the floor of which was strewn with alder cut- 

 tings about a foot in length. The branches were generally cut 

 diagonally, and one was as much as half an inch in diameter. The 

 animals seem to well deserve their name of "mountain beaver". 



Miss Alexander caught three males in one limited area at Jack- 

 son Lake, but on the whole the idea that these animals live in colo- 

 nies did not seem to be correct. They may do so at certain times 

 of the year, as during the breeding season and until after the young 

 ones are full grown; but we never trapped more than one animal 

 at a single set of burrows. 



On the Salmon Eiver we found the mountain beavers making 

 what we called "hay" — large bunches of green plants of various 

 kirn Is out up and spread out as if to dry and to be used later. (See 

 pi. 16, figs. 3, 4). On a sidehill down which ran several small 

 streams among alders and poplars there was a collection of bur- 

 rows more extensive even than any found at Jackson Lake. These 

 were situated both near the stream and out in the more open, drier 

 ground. The runways led under roots and over rocks, with open- 

 ings at short intervals, and there were plain runs out into the 

 brush where short branches ran from each main tunnel, somewhat 

 like a gopher working, with a dump of earth at each terminus. 



Citellus douglasii (Richardson) 

 Douglas Ground Squirrel 

 Most of our camps were above the range of this ground squirrel. 

 At Scott River it was common in the sandy ground along the 

 numerous irrigation canals leading off from the river. We caught 

 a good many more individuals than we wanted, especially of young 

 ones. The weather was very warm and their greasy skins slipped 

 quickly. The occurrence of the species at Castle Lake, however, 



