Color. Above from very dark brown, nearly black, to pale brown; 

 sides of head and body chestnut brown, under fur bluish gray. Feet 

 dark brown; tail black. Specimens vary greatly in the hue of 

 the fur. 



Measurements. Total length, 538; tail vertebra', 250: hind 

 leg, 86. 



a.—pallidus. {Fiber), Mearns, Bull. Am. Mus. Nat. Hist., 1890, 

 p. 280. 



Type locality. Fort Verde, Central Arizona. 



Geogr. Distr. Probably from Arizona to the central plains of 

 Montana, the lateral limits not determined. 



Genl. Char. Size small, about two-thirds that of typical form. 

 Skull like that of eastern muskrat, but smaller. 



Color. Rustj' brown, paler beneath; scattered hairs of tail liver 

 brown. 



Measurements. Total length, 500; tail vertebra', 203; hind 

 foot, 69. 



b.—rivalicus. {Filter), Bangs, Proc. Bost. Soc. Nat. Hist., 1S95, 



P- 541- 



Type locality. Burbridge, Louisiana. 



Geogr. Distr. Lower Mississippi region and swampy coasts of 

 Louisiana and Alabama. 



Genl. Char. Smaller than F. zibethicus, color dull and darker. 



Color. Above clove brown to black, base of hairs mouse gray; 

 beneath vandyke or clove brown; fur on under side of legs and arms 

 brownish white at base. A spot at middle of sides with under fur 

 white at base. Feet and tail black. 



Measurements. Total length, 530; tail vertebrae, 222; hind 

 foot, 81. 



c.—aquAlonius. {Fiber), Bangs, Proc. N. Eng. Zool. Club, 1899, i, 

 p. III. 



Type locality. Rigoulette, Hamilton lulet, Labrador. 



Geogr. Distr. Labrador. 



Genl. Char. Smaller than F. zibethieus ; blacker, hind foot 

 smaller; rostrum long, slender; nasals long, narrow. 



Color. Above, long hairs tipped with black, those of rump and 

 sides with burnt umber; beneath, throat and lower abdomen grayish; 

 long hairs russet. Tail black; feet dusky. 



Measurements. Total length, 549; tail vertebra?, 249; hind foot, 73. 

 Skull: occipito-nasal length, 61.4; zygomatic width, 40; basal length, 

 58.4; mastoid width, 26.6. 



