150 THE BIRDS OF COOKHAM AND THE NEIGHBOURHOOD. 
and I shall then hope to be able to lay before my readers some 
more definite remarks on this species. I shall also, I hope, by 
that time be in possession of a more complete series of skins, so 
as to be able to bear out my present conjectures by the actual 
observation and possession of specimens. Should any of my 
friends find any with a deep rufous colour on the breast, I shall 
be glad at all times to receive them at the office of the Zoological 
Society, Hanover-square, London, W. 
Chelidon. 
14. Chelidon urbica. The Common Martin. 
The Martin may be distinguished from the foregoing. 
species by the white mark on the lower part of its back, which is 
very conspicuous when flying, and also by its mode of flight, 
which is always swifter and less laboured than that of the Swallow. 
It also generally flies high in the air, which is seldom the case with 
the Swallow, who skims along the ground after insects. The 
present species is very fond of frequenting the waterside, and may 
often be seen in groups of three or four together sitting by the 
side of the river and dipping themselves. The Martin is also 
very fond of dusting itself in the middle of the roads. 
Cotyle. 
15. Cotyle riparia. The Sand Martin. 
There are several gravel pits and other situations near Cookham, 
which form suitable breeding-places for the Sandmartin, and the 
bird is very common there in summer. It arrives sooner than 
the Martin or the Swallow, and departs before them. 
Fam, CypseLipm. 
Cypselus. . 
16. Cypselus apus. The Common Swift. 
There is scarcely anyone living in the country who is not 
acquainted with the Swift, or who does not welcome him as the 
harbinger of spring, and equally regret his departure as the sure 
sign that winter is approaching. The Swift is one of tho latest 
birds to arrive and tho earliest to go. It breeds under the eaves 
of houses in the village, penetrating far out of reach under the 
roof. Ihave taken its nest on Peterborough Cathedral; where 
thousands breed every year. 
