SYLVIA.] AVES INSESSORES. Ill 



Common in the southern, western, midland* and some of the northern 

 counties, but not generally diffused. In Cambridgeshire very rare. 

 Haunts woods and tall trees ; being first heard towards the end of April 

 or beginning of May. Note very peculiar, resembling the word twee 

 repeated several times in succession, at first slowly, but afterwards in a 

 hurried manner, and accompanied by a singular shake of the wings. 

 Nest placed on the ground, of an oval form, constructed of dry grass, 

 dead leaves, and a little moss, lined with finer grass and a few hairs. 

 Eggs six in number. 



57. S. Trochilus, Lath. (Willow-Wren.) Upper 

 parts pale olive-green, tinged with yellow : under tail- 

 coverts yellowish white: wings with the second quill equal 

 to the sixth ; the third, fourth, and fifth, with their outer 

 webs sloped off at the extremity. 



S. Trochilus, Temm. Man. d'Orn. torn. i. p. 224. Yellow Wren, 

 Mont. Orn. Diet. Selb. Illust. vol. I. p. 226. pi. 47. f. 3. Willow- 

 Wren, Bew. Brit. Birds, vol. i. p. 257. 



DIMENS. Entire length four inches eleven lines : length of the bill 

 (from the forehead) four lines, (from the gape) six lines; of the tarsus 

 nine lines ; of the tail two inches three lines ; from the carpus to the end 

 of the wing two inches six lines and a half: breadth, wings extended, 

 eight inches. 



DESCRIPT. Distinguished from the last principally by its paler colour, 

 and shorter wings ; the difference in size not very obvious. Upper parts 

 pale olive-green, with a yellowish tinge, inclining in some specimens 

 to cinereous : from the base of the bill a bright streak of primrose-yellow 

 extending over each eye to the temples, but narrower than in the S. 

 sibilatrix: all the under parts yellowish white ; the yellow tinge darkest 

 on the breast, sides, axillse, and ridges of the wings ; palest on the middle 

 of the belly : quills and tail brownish ash, faintly edged with olive-green ; 

 the latter extending eleven lines beyond the tips of the folded wings, 

 with the two middle feathers shorter than the others : base of the under 

 mandible yellowish : feet light brown. Obs. The colour of this species, 

 especially the intensity of the yellow tinge, varies much in different 

 individuals. The variation, however, results more from a difference of age 

 than of sex. The male and female are equally pale in the adult state. 

 The yellowest birds, which are also generally the smallest, occur in the 

 early part of the Spring, and appear to be the young males of the pre- 

 ceding year. (Egg.) White, with numerous small specks of pale red : 

 long. diam. seven lines and a half; trans, diam. six lines. 



Of frequent occurrence in gardens, plantations, hedges, willow-grounds, 

 and a variety of other situations. On the whole a much more generally 

 diffused species than the last, but, according to Montagu, does not extent 

 so far westward. Song pleasing, but simple, consisting of several plain- 

 tive notes in a regularly descending scale; heard from the middle of April 

 to the beginning of July. Nest placed on the ground, nearly spherical, 

 with a small opening at the side near the top; composed of dry grass, 

 stalks, and other herbage, and profusely lined with feathers. Eggs five 

 to seven ; hatched the end of May or beginning of June 



58. S. Hippolais, Lath. (ChiJf-Chaff.) Upper parts 

 olive-green, -tinged with yellow; beneath yellowish white: 



