OF NORTH AMERICA. 107 
which has been considered sufficiently distinct 
to form a new species. But they are suff- 
ciently similar to be considered as one and 
the same, so far as our purpose goes, and in 
view of the numerous variations of individual 
plumage, the subdivision is extremely prob- 
lematical, except to the expert. 
119. WHITE-TAILED PTARMIGAN. 
Lagopus leucurus. 
Habitat— Rocky Mountains. Size and 
appearance similar to No. 118; but the tail 
remains white throughout the year, and the 
wings and abdomen are of this color in the 
summer plumage. Found on the mountain 
ranges, from the timber-line upward, coming 
lower down in the winter, as the other forms 
come southward at the same time. 
120. PRAIRIE HEN. 
PINNATED GROUSE. 
Tympanuch us americanus. 
Predominant color grayish-brown, heavily 
barred with black. Head buffy, underside 
dirty white, barred with brown. Top of head 
and stripe on each side, black. Tail dusky, 
tipped with white. The most peculiar feature 
of this bird is the black tuft of feathers 
