616 CYPSELUS MURAIUUS. 



forked, the lateral feathers an inch and a quarter longer than 

 the medial, and a little recurved. 



The bill, feet, and eyes are black. The general colour of 

 the plumage is blackish-brown, generally glossed with slight 

 greenish reflections ; the throat whitish ; the outer primaries 

 darker than the rest. 



Length to end of lateral tail-feathers 7i inches ; extent of 

 wings I65; wing from flexure 7; tail 85, the middle fea- 

 thers 2 ; bill along the ridge i, along the edge of lower man- 

 dible i§ ; tarsus j% ; first toe ^%, its claw ^^| ; second toe -f|, 

 its claw /j ; third toe j^, its claw j^ ; fourth toe jl, its 

 claw /j. 



Female. — The female is a little lighter above, and has the 

 feathers of the lower parts slightly margined with a paler tint, 

 the throat whiter, its feathers dusky on the shafts. 



Length to end of tail 7i2 inches; extent of wings 151, 

 wing from flexure 6f ; tail 3j ; bill along the ridge j^|, along 

 the edge of lower mandible j% . 



Variations. — In adult individuals, the variations are not re- 

 markable. 



Changes of Plumage. — This species arrives in Britain in 

 perfect plumage. The colours fade considerably as the sum- 

 mer advances, becoming of a browner tint, and by the middle 

 of August the plumage has acquired a bleached appearance. 



Habits. — The Black Swift arrives in the south of Scotland 

 in the beginning of May. Mr Selby says that " it is seldom 

 seen in the northern parts of England before the end of May 

 or the beginning of June ;"*' but this appears to be a mistake, 

 for in Edinburgh it always comes before the tenth of May, and 

 even in the very severe weather of 1837 it was seen at Canon- 

 mills by my son on the 1st, and at Newington by myself on 

 the 3d of May. In the south of England it is stated to appear 

 between the 20th of April and the 1st of May ; and Mr Har- 



