THE CLASS BIEDS. 



341 



and some by twilight ; and of these latter, it is sufficiently 

 remarkable that they are of a sombre colour, with downy 

 pinions, so that they strike the air without any noise. To 



Fig. 333. Pallas ; Land Grouse of China. 



this class belong the owl and goat-suckers, &c ; their habits 

 and structure are strictly in unison. 



Fig. 334. The Ptarmigan (Lagopus), White Grouse. 



447. The species known to naturalists amount to seven 

 thousand, and their classification is difficult by reason of the 

 great uniformity of their structure. Their distinguishing 

 characters, as being in relation with their regime, have been 

 taken chiefly from the conformation of the bill and legs. 



