76 TtFRDID^. 



They moult twice in the year ; and the young birds are scarcely to 

 be distinguished from adults. With the exception of one species, 

 which, for reasons hereafter given, I have divided into five sub- 

 species, there is in no one species anj- great variation of size ; nor 

 does there appear to be any constant difFerence in size between the 

 sexes. In every species the tarsus is scutellated in front. 



All the species of this genus have considerable powers of song. 



The basin of the Mediterranean appears to be the centre of dis- 

 tribution of this genus — one or two species extending their range 

 more to the east, one of them as far as Lake Baical. 



Key to the Species. 



A. General colour of the upper parts olive-green ; 



imderparts yellowish ; tail nearly even. 



(Subgenei'ic group Hypolaides.) 

 a. Second primary generally between the fourth and 



fifth ; bastard primary generally shorter than 



the primary-coverts, never extending more than 



005 inch beyond them, Length of wing 3 2 to 



2-9 inches. Legs bluish grey _ icterina, p. 77. 



h. Second primary generally between the sixth and 



seventh ; bastard primary exceeding the primary 



coverts by 01 to 0-2.3 inch. Length of wing 



2-6 to 2-.38 inches. Legs pale browji polyglotta, p. 79. 



B. General colour of the uppfr-r parts brown or grey ; 



underparts white or pale brown ; outside tail- 

 feathers 0-15 to 0-2 inch shorter than the longest. 



(Subgeneric group Idun.*:.) 



a. Bastard primary shorter than the primary-coverts, 



or not exceeding them more than 0-05 inch . . 

 a'. Second primary intermediate between the 



fourth and filth; bastard primary falling 



short of the primary-coverts by 0-2 to 0'2o 



inch. Length of wing 3-4o to 3-3 inches . . oUvetoriim, p. 79. 

 b'. Second primary intermediate between the fifth 



and sixth ; bastard primary falling short of 



the primary coverts by O'l inch, or extending 



005 beyond them. Length of wing 305 to 



2-8 indies languida, p. 80. 



b. Bastard primary exceeding the primary-coverts by 



at least 01 inch, 

 e'. General colour of the upper parts pale sandy 



brown or isabelliue brown obsoleta, p. 80. 



d'. General colour of the upper parts darkish rufous 

 brown or grey. 

 a". Second primary generally intermediate be- 

 tween the fifth and sixth ; bastard primary 

 exceeding the primary-coverts from O'l to 

 0-3 inch. Length of wing 2-75 to 2 5 inches, 



culmen 07 to 0-6 pallida, p. 82. 



b". Second primary generally intermediate be- 

 tween the fiftii and sixth ; bastard primary 

 exceeding the primary-coverts from 0'2 to 

 0-32 inch. Length of wing 2 75 to 2-6 



