THE BIRDS OF HELIGOLAND 295 



ciliosus, and in general aspect resembles a very freshly-coloured 

 specimen of the latter species. Its upper parts, however, are of a 

 purer and lighter olive green, and the lemon yellow markings of 

 the head and neck are considerably purer and richer. This remark 

 especially applies in the case of the eye-streaks, and a stripe of the 

 same colour extending from the bill across the crown of the head 

 deep down to the nape of the neck. The bands on the wings are 

 also broader, and of a purer yellow. The rump is of a rich lemon 

 yellow, its colour being sharply marked oft' from that of the back, 

 and it is by this feature especially that the bird may be dis- 

 tinguished at a glance from the preceding species. 



The only measurements I am able to give from a fresh example 

 are those of the above-mentioned wing. These, however, com- 

 pletely agree with those of four examples collected in eastern 

 Siberia. The total length of the wing is T92 in. (49 mm.); the 

 third, fourth, and fifth flight-feathers are of equal length, and form 

 the tip of the wing; the sixth recedes by - 04 in. (1 mm.); the 

 second is of the same length as the eighth, -23 in. (6 mm.) shorter 

 than the three longest primaries, and '20 in. (5 mm.) longer than 

 the longest of the three last flight-feathers. 



A comparison of this wing with Siberian and Indian skins has 

 revealed a fact which seemed hitherto to have escaped observation, 

 viz. that there exists a similar case of difference as between the 

 preceding species the Siberian S. superciliosa and the Indian 

 S. humei inasmuch as Sylvia proregulus is not identical with the 

 southern very closely related form, but presents constant differ- 

 ences from the latter, both in coloration of plumage and the 

 relations of the flight-feathers. 



Skins from India are described as S. proregulus ; and Seebohm, 

 the Catalogue of the Birds of the British Museum, vol. v. p. 71, 

 places the name Phylloscopus proregulus after seven Indian and 

 one Siberian example ; whereas a careful examination proves that 

 these two birds form two separate and independent species, like 

 8. superciliosa and 8. humei, 8. tristis and S. fuscata, S. trochilus 

 and S. rufa, and probably some others. 



In colour the Indian species is distinguished from its northern 

 relative, like 8. humei, and even in a higher degree, by the deeper 

 olive brown (olivenbraun) colour of the plumage; the beautiful 

 sibilatrix-like lemon yellow marking on head and neck, which 

 distinguishes the latter species to such advantage, is wanting in 

 the former; the stripe on the crown, and the eye-streaks, are 

 dull olive brownish yellow (olivenbraungelb) ; the back is olive 

 brown, not olive green, as in S. proregulus ; and all the underside of 

 a dull olive yellow (olivengelb), which on the upper breast and 



