io6 HANDBOOK OF BRITISH BIRDS 



(Chelidonium) and Swallow's stone said to be found 

 in the nest, see a chapter in my " Essays on Natu- 

 ral History," 1880, pp. 27G-284. 



Swallows are infested by at least three genera 

 of parasitic dipterous insects — Ornithomyia, Ste- 

 nopteryx, and Oxypterum. Figures of these flies 

 are given in Walker's "Insecta Britannica, Diptera," 

 vol. ii. tab. xx. 



MARTIN. Hirihndo urbica, Linnseus. PI. 17, figs. 5, 5a. 

 Length, 5-25 in. ; wing, 4-25 in. ; tarsus, 0*4 in. 



A summer migrant, arriving in April, and usually 

 departing some weeks before the Swallow, which 

 lingers here until October, and often until Novem- 

 ber. The difference in the mode of nidification 

 with the two species should be too well known to 

 need description here. Suffice it to state that it is 

 the House Martin which builds under the eaves, and 

 is often dispossessed by the Sparrow. Where House 

 Sparrows are destroyed. House Martins increase. 

 This was particularly observed by Colonel Kussell 

 at Stubbers, near Komford ; see also R. J. Howard 

 in Mitchell's "Birds of Lancashire," 2nd edit. 



Before human habitations were constructed of 

 stone-masonry, the Swallows built their nests in 

 caves, and the Martins on the face of cliffs; in 

 several localities that could be mentioned they 

 still continue to do so. See Zool., 1882, p. 437; 

 1883, p. 34; 1884, p. 470; 1887, p. 373; and 

 1894, p. 400. 



