280 Bulletin American Museum of Natural History. [Vol. XX, 



8. Of this number only about 23, or about one sixth, are 

 fully adult. These consist of 14 females and 9 males, and 

 measure as follows: 9 males, total length, 143 (140-149); 

 tail vertebrae, 35 (32-38); hind foot, 19 (18-20); ear, 13 

 (1214): 14 females, total length, 144.4 ( I 37~ I 53)i tail ver- 

 tebrae, 34 (30-40); hind foot, 19 (18-20); ear, 13.5 (12.5- 

 15). Of the remainder quite a number are so young as to 

 fall below no in total length, while about one third fall be- 

 tween no and 120, and another third between 120 and 130. 



These statistics bear out the statement that orca averages 

 distinctly larger than true dawsoni. 



This species was found to be very plentiful at all points 

 where trapping was done. Their haunts are " logs and mossy 

 banks and stumps in the spruce timber, but in a number of 

 instances they were found digging burrows in moist earth in 

 interspaces in the timbered region. Specimens were often 

 found with their mouths filled with the seeds of some herb." 



9. Microtus miurus Osgood. ALASKA MOUNTAIN VOLE. 

 One hundred and twenty-six specimens, all taken at Sheep 

 Creek, Sept. 12-21. Only 24, or about one fifth, are adult, 

 and of these only five are males, although the sexes are about 

 equally represented in the series as a whole. Measurements: 

 5 males, total length, 154 (145-158); tail vertebrae, 26 (22- 

 29); hind foot, 19.8 (19.5-20); ear, 13.4 (12-14): 19 females, 

 149.7 (140-159); 29 (24-30); 19.7 (19-20); 13.2 (12-14). 



According to Mr. Anderson's notes this species was found 

 ' ' only about the edges of some mossy swamps in little valleys 

 between the hills." It was taken only at the "upper sheep 

 camp," on Sheep Creek. 



10. Microtus operarius (Nelson). NELSON'S VOLE. One 

 hundred and seventy-three specimens, collected as follows: 

 Muller Bay, 96, May 23-June 12; Seldovia, 48, June 27 

 August 19; Sheep Creek, 5, August 20-22; Barabori, 4, Au- 

 gust 24, 28, and Sept. i; Caribou Camp, 8, Sept. 4-8; Moose 

 Camp, 12, Sept. 27-Oct. 8. 



This was the only species of Microtus taken on the Alaska 



