38 TUKDID^. 



distiuct. The "Willow-Warblers are essentiall)^ fly-catcliers in their 

 habits, and may constantly be seen catching flies upon the wing. 

 Their bills, if not very wide, are considerably depressed at the base, 

 and the rictal bristles are well developed. Most of the species are 

 migratory ; the wing is long, flat, and pointed, whilst the bastard 

 primary is very small ; and the range of migration extends over 

 thousands of miles. The migrations of others is confined to the 

 plains within sight of the mountains where they breed. In these the 

 wing is shorter, more concaved to fit the body, and rounded, whUst 

 the bastard primary is larger, the vital energy required for its produc- 

 tion not having been absorbed in lengthening the adjoining primaries. 

 The tail is generally nearly even and frequently forked. All the 

 species of the genus are quietly coloured, the upper parts varying 

 from yellowish green to huffish brown, and the underparts from 

 yellow to buff or white. The axillaries and under wing-coverts are 

 yellow, a character which will serve to separate all the species of 

 the genus from the nearly allied genera. Most of the species whose 

 niditication is known build a semi-domed nest on or near the 

 ground, and lay white eggs spotted with red. 



In their breeding- range these birds are PaliBarctic, ranging from the 

 Atlantic to the Pacific, one species beingknown even to cross Behring's 

 Straits into Alaska. Several species extend their range further north 

 than the limit of forest-growth. Those species which do not breed 

 within the Palaearctic Eegion ascend the Himalayas until they reach an 

 elevation whore they can enjoy a Pala-arctic climate. The southern 

 winter range of the genus extends in Africa to the Cape of Good 

 Hope, and in Asia to Ceylon and the islands of the Malay archipe- 

 lago, but no species has as yet been found in Australia. 



Key to the Sjpecies. 



A. Bill broad at the base and rather flat, with 

 well-developed rictal bristles, almost Musci- 

 capine ; upper mandible dark, under mandible 

 paler. In lawhraded plumaf/e the gi'eater 

 wing-coverts have pale tips, forming a con- 

 spicuous bar across the wing ; the median 

 wing-coverts have also more or less distinct 

 pale tips, forming an obscure upper wing-bar. 



(SuDgeneric group Acanthopneust^.) 

 a. No mesial line on the crown. 



a'. Second primary as long as or longer than 

 the sixth. 

 a". Exposed portion of bastard primaiy 

 0-3 to 0-35 inch in adults, 04 to 0-45 

 in birds of the year. Throat and 

 belly in spring plumage nearly white. 

 Length of wing 2v to 2'4 inches .... borealis, p. 40. 

 b". Exposed portion of bastard p)imary0'5 

 to 0-G inch. The whole of the under- 

 parts in all plumages greenish yellow. 

 Length of wing 2-85 to 2-6 inches .... xanthodryas, p. 42. 



