OTIDIDAE 



261 



is Y-shaped, and often ancylosed with the sternmn, the syrinx is 

 tracheo-bronchial. An after-shaft is present, and the down, which 

 is uniform in tlie young only, is in them mottled with hlack and 

 lighter tints. A most remarkable phenomenon, moreover, is 

 the gular pouch, opening under the tongue, found in the male of 

 some examples of Otis tarda, during the breeding season. This 

 poucli becomes very small or vanishes altogether at other times of 



Fig. 54. — Great Bustard. Otis tarda, x ^ or ^^. 



the year, and seems to be restricted to adult birds. Similar, 

 but smaller, processes have been observed in Evpodotis kori, 

 E. edwardsi and, it is said, Otis tetrax ; while dilatations of the 

 oesophagus have been recorded in E. australis and Neotis denhami. 

 Otis tarda, the Great Bustard, which, as a native, only became 

 extinct in Norfolk about 1838, used to extend from East Lothian 

 to Dorset, but is now merely an occasional visitor to Britain. 

 The upper parts are mottled with rufous, buff, and blackish- 



