Occasional Papers of the Museum of Zoology 3 



The interior of Alaska north of the Alaska Range is made up 

 mostly of broad, nearly level valleys and massive, rounded hills 

 which rise in many cases above timber-line into high, isolated 

 domes. The older forest fringing the streams and extending over 

 the sunny slopes of the hills is mostly of white spruce and Alaska 

 paper birch, though on islands and on newly formed river bars 

 there are thickets of willows and alders and some areas of poplars. 

 The extensive forests of the region, however, are of stunted black 

 spruce, which covers the lower hills and the greater parts of the 

 valleys. In the valleys are numerous small lakes, each usually 

 surrounded by a fringe of swamp. Growths of niggerheads and 

 patches of blueberries occur also in the valleys. Timber-line at 

 Tanana is at about 2,000 feet; above this are numerous patches 

 of blueberries and dwarf birches, with occasional growths of scrub 

 willows or alders. On the ridges are low growths of grass and a 

 scanty growth of sphagnum. Talus and rock exposures are 

 rather rare even on the higher slopes. 



These conditions continue westward to the tundra along 

 Bering Sea, which along the Yukon is met at Andreafski, and on 

 the Kuskokwim at Bethel. Between the two rivers tundra 

 extends farther inland, being found on the Kuskokwim- Yukon 

 portage between Kaltshak and Russian Mission-on-the- Yukon. 



To the lists of vertebrates found by the author in the different 

 habitats have been added a number of records from Osgood' and 

 Blackwelder.^ The lists are very incomplete, but no species has 

 been included in a list without positive evidence of its occurrence 

 in that particular habitat within the region. 



Mr. Edward A. Preble and Dr. H. C. Oberholser gave much 

 help in working up the taxonomy of the mammals and birds 

 respectively. Dr. Frederick V. Coville assisted with the plant 



' W. H. Osgood, op. cit., 22-45, ^"d North American Fauna, No. 30, 

 1909, 13-44- 



' Eliot Blackwelder, Auk, XXXVI, 1919, 57-64. 



