102 HIRUNDINID^, 
migration ; and I have never been able to detect it remaining 
to nest. The earliest date of arrival noticed was the 8th of 
April; from then till the 1st of May they pass in great 
numbers_, returning late in September. The latest date on 
which they were observed was the 17th of October 1870, 
when I killed one in an old owl's cage, where there was a lot 
of carrion which attracted flies ; and, again, in 1871 I noticed 
them on the 16th of October. 
The Collared Flycatcher [Muscicapa albicolUs) I have not 
noticed, nor have I seen a specimen from either side of the 
Straits. 
122. BuTALis GRisoLA (Linn.). The Spotted Flycatcher. 
Spanish. Papamoscas. 
''This Flycatcher is very common near Tangier, where 
they arrive in April and May in pairs and small flights, some 
remaining to nest, the rest passing across the Straits to 
return in September, when they disappear. Near Rabat 
they are called Sorsh by the Arabs.""^ — Favier. 
The Spotted Flycatcher is exceedingly numerous near 
Gibraltar, chiefly nesting in the pine-woods. It was first 
seen on the 11th of May 1870, on the 3rd of the same month 
in 1871, and on the 8th in 1874. The first egg obtained was 
on the 24th of the same month. I regret not to have any 
note of their departure ; but it is previous to the middle of 
September. 
Family HirundiniDjE. 
123. Chelidon urbica (Linn.). The House-Martin. 
Spanish. Vencejo. 
" As common as the Swallow near Tangier, this species is 
seen in flights on passage, crossing to Europe in February, 
returning in September and October, frequently travelling in 
company with Hirundo rustica, and, as in their case, remaining 
to breed in some numbers. They often make their nests 
touching one another, as many as sixty being joined together; 
the entrance-hole is sometimes at the side, sometimes in the 
centre, according to the position of the nest. They are 
