48 



NOETH AMEEICAN EAUNA. 



[No. 37. 



(43); least interorbital breadth, 17.8-22.2 (20.1); breadth of rostrum, 

 19-20.5 (19.8); maxillary tooth row, 19.3-20.8 (20). Adult female:^ 

 Condylo-basai length, 78.2-83.8 (80.4); palatal length, 44.1-47 (45.1); 

 postpalatal length, 29.4-33.5 (31.2); length of nasals, 30.8-34.8 (32.4); 

 zygomatic breadth, 53.2-54.5 (53.9); breadth across mastoids, 37.4- 

 41.6 (39); least interorbital breadth, 18.5-19.7 (19.1); breadth of ros- 

 trum, 17-19.3 (18.3); maxillary tooth row, 19.7-20.5 (20.1). 



Bemarks. — This subspecies, one of the handsomest members of the 

 flaviventris group, is abundant and generally distributed in the 

 northern Rocky Mountain region of Montana, Idaho, and Wyoming. 

 Closely related to dacota of the Black Hills, it probably intergrades 

 with that race in central Wyoming, Specimens from the northern 

 Umit of its range (Horse Plains and Weeksyille, Mont.) are consider- 

 ably paler than the typical form, shomng approach to avara. The 

 southern Emits of the range of nosopliora are not known, only a few 

 specimens having been seen from the Wasatch Moimtains, and none 

 from the Uinta Mountains, Utah. Intergradation with engelhardti 

 probably occurs where their ranges meet. 



A brown phase of this subspecies, having the tips of the hairs 

 white instead of cinnamon-buff and the underparts mixed brown and 

 buff instead of red, occurs in some locahties with the normal phase. 

 Several immatiu-e specimens, varying somewhat in color, have been 

 examined from near timber hne in the Wind River Mountains, Wyo. 

 An adult female in very worn pelage from timberUne in the Bear- 

 tooth Mountains, Mont., is similar to those from the Wind River 

 Mountains, but the brown of the upperparts is paler, evidently faded, 

 and the underparts are mixed chestnut and black, shaded with 

 tawny. Some specimens in this phase somewhat resemble ex- 

 ternally the members of the monax group but the skulls are typical 

 of nosofhora. 



This marmot serves as a host for the Rocky Mountain fever tick 

 (Dermacentor venustus) and thus aids in the dissemination of the 

 deadly spotted fever, particularly along the western, side of the 

 Bitterroot Valley, Mont., where the disease occurs in its most virulent 

 form. 



Specimens examined. — Total number, 62, as follows: 



Idaho: Bear Lake (east side), 1; Bridge, 1; ConaDt Creek (upper Snake River), 

 1; Grace, 2; Henry Fork of Snake River, 1; Irwin (20 miles northwest), 1; 

 Island Park, Snake River, 1; Moody Creek (upper Snake River), 1; Preuss 

 Mountains, 1; Sawtooth National Forest, 2; Teton Basin, 1. 



Montana: Bass Creek (in mountains northwest of Stevensville), 3; Beartooth 

 Mountains, 3; Bozeman, 1; Como Lake, 1; Florence, 2; Horse Plains, 4; 

 Jardine, 1; Pryor Mountains, 2; Ross Fork (15 miles above Darby), 2; Weeks- 

 ville, 1; Willow Creek (in mountains east of Corvallis), 3. 



» Five specimens from Bitterroot Valley, Montana. 



