422 CONTRIBUTIONS TO A REVISION OP THE 



mm.; breadth of skull, 99 mm. Maximum length of old males, measured by Dr. 

 Mearns, 1130 mm.; of the tail paddle, 285 by 155 mm. 



Remarks. — Dr. Mearns' comparisons of frondator with canadensis were evidently 

 not made with the largest specimens of the latter, as I have examined some whose cra- 

 nial and body measurements are about equal to the maximum recorded by him for 

 frondator. Nevertheless, there is little doubt that the larger size of average frondator is 

 well established. Its long hind foot, broad tail and light coloration distinguish it 

 immediately from canadensis. Its approach to pacificus is solely along the line of great 

 size as indicated by the length of body and hind foot, but in cranial characters, as also 

 in color, it is' farthest removed from that race. The close anatomical relation of frondator 

 to carolinensis has been mentioned. 



Specimens Examined. — Montana, 1 skin with skull ; Wyoming, 1 skull. 



Pacific Beaver. Castor canadensis pacificus, subsp. nov. 

 Plate XXI ; Fig. 1. Plate XXII ; Fig. 1. 



Type Locality. — Lake Kichelos, Kittitass county, Washington ; altitude about 8000 

 feet. Type, No. 1077, ad. 9, in the collection of S. N. Rhoads ; collected in April, 

 1893, by Allan Rupert. 



Geographic Distribution. — Pacific sloj)e, of America, from Alaska to California. 



Color. — Above with very uniform, dark and glossy reddish chestnut overhair, 

 almost concealing along dorsum the seal-brown underfur. Top of head like back ; sides 

 of head, throat, rump, thighs and vent not decidedly lighter than back and belly as in 

 the other forms, these parts paling to walnut brown. Overhair of sides and under parts, 

 between seal brown and broccoli brown ; under fur of belly drab gray at the roots ; hind 

 feet dark seal brown ; fore feet and limbs, dark wood brown. Ears black. 



Anatomical Characters. — Size, largest of the canadensis group, but of more slender 

 build, the skeleton throughout being of much greater longitudinal and lesser lateral 

 dimensions than in the other forms. Tail and hind foot relatively long. Skull large, 

 relatively narrow, with long, narrow rostrum and nasals, the latter with outer margins 

 nearly parallel and reaching basally decidedly beyond the premaxillaries. Upper molar 

 dentition weak, the crowns of molar teeth rectangular. 



Measurements. — Of the type from carcass: Total length, 1143 mm.; tail vertebra;, 

 330 mm.; (from relaxed skin) scaly portion of tail, 295 mm. by 122 mm.; hind foot, 185 

 mm.; length of skull, 142 mm.; breadth of skull, 101 mm.; length of nasals, 53.6 mm.; 

 breadth of nasals, 24 mm.; average length and breadth of five skulls from Tacoma and 

 Lake Kichelos, Washington, 144 mm. by 99 mm.; average nasal length and breadth of 

 same, 54 mm. bv 23 mm. 



