370 University of California Publications in Zoology C VoL - 12 



Lake, south fork of Salmon River, Wildcat Peak, and head of 

 Grizzly Creek. Upon this series was based the description of Aplo- 

 dontia chryseola as a new species showing nearest affinities with 

 A. californica of the central Sierra Nevada (see Kellogg, 1914, p. 

 295). This species proves to be not closely related to the coast 

 form, A. phaea, as its golden brown coloration might seem to indi- 

 cate. Cranial and other characters lead the writer to conclude 

 that chryseola is derived from californica stock, the latter thus 

 having invaded the territory westwardly towards the coast through 

 the Trinity region. For cranial characters see table of measure- 

 ments, page 371, and photographs, plate IS. 



Our first systematic search for signs of mountain beaver was 

 begun at Jackson Lake, Siskiyou County. Here clumps of alder 

 grew on sidehills from which trickled small streams of water. This 

 seemed ideal ground for the animal, but the first real sign was 

 found on drier ground where a runway was located between two 

 such groups of alders. The tunnel, or runway, was finally traced 

 direct from one alder patch to the other through a growth of wild 

 plum, and measured seventeen meters in length. There were a dozen 

 or more exposures of the runway. Although it seemed to be con- 

 tinuous, the tunnel proved, upon examination, to be disconnected 

 at about a third of the distance, as it took a decided turn down 

 the hill, while the one in line with it tended diagonally up hill. 

 Before the first section of tunnel took the downward turn there 

 was a small side exit, showing that the animals foraged abroad 

 into the rather open wild plum grove as well as into the alder 

 thickets. There may have been underground connections between 

 the two sections. The first tunnel ran back into the alders, and 

 there was no visible exit within a radius of several yards. The 

 tunnel throughout its exposed length was dry and looked to be in 

 recent use. In hunting among the alders we found several old 

 burrows which now serve as underground channels for small streams. 



Miss Alexander found other Aplodontia burrows north of Jack- 

 son Lake in alders along one of the main tributaries of Jackson 

 Creek. In places the ground was literally honeycombed by them. 

 In such a multiplicity of runways it was hard to select just the 

 right places for the traps. Fresh sign was found near an old fallen 

 tree by the stream. The tree was about forty-five feet long and 

 the main tunnel seemed to run lengthwise underneath it with exits 



