THE BANK-MARTINS. 329 



towards the middle or end of April, and leaves again from 

 September onwards ; on raie occasions Martins have been ob- 

 served in England in November and December. Like all of 

 the family, the House-Martin is untiring on the wing in pursuit 

 of the gnats and small flies on which it feeds. It is not only 

 found in country districts, but even frequents towns and builds 

 its clay nest under the sheltering eaves of many a suburban 

 villa. Soon after its arrival it may be seen flying down to a 

 puddle in the road or a pond to get the mud with which it 

 makes its nest. Sometimes the nests are placed against rocks, 

 especially in those localities where there is no sheltering build- 

 ing to be made use of. 



Nest. — Made of small nodules of mud, the nest being lined 

 with dry grass and a few feathers. It is rather large, and has 

 the aperture near the top, from which the parent birds and the 

 young are often seen protruding their heads. 



Eggs.— From four to six in number, and glossy white. Axis, 

 o"75-o - 85 inch; diam., o"55-o , 6. 



THE BANK-MARTINS. GENUS CLIVICOLA. 



Clivicola, Forster, Syn. Cat. Brit. B., p. 58 (181 7). 



Type, C. riparia (Linn.). 



These birds are distinguished from the House-Martins and 

 the Chimney-Swallows by several characters. They have a 

 square tail, without the elongated outer feather, which dis- 

 tinguishes the genus Hirundo i and they lack the feathered toes 

 which characterise the genus Chelidon. Curiously enough, 

 however, this feathered element in the feet is not altogether 

 absent in the genus Cot He, for at the back of the base of the 

 tarsus there is a tiny tuft of feathers. 



There are nine different species of Cottle known to science, 

 two Palaearctic, six Ethiopian, and one Indian. The species of 

 Europe, C. riparia, is also a common North-American bird, win- 

 tering in the Neotropical Region. 



I. THE SAND-MARTIN. CLIVICOLA RIPARIA. 



Hirundo 1-iparia, Linn., Syst. Nat., i., p. 344 (1766); Macg., 

 Br. B., Hi., p. 595 (1840); Seeb., Br. B., ii., p. 184 

 (1884). 



