PASSERINE. FISSIROSTRES. 



295 



to which their four toes, all pointing forward, enable 

 them to cling. Our common Swift, (C. Apus,) the 

 largest of the English species, continues with us a 

 very short season, coming the latest, and retiring 

 the earliest. It builds in crevices of towers and 

 steeples, and under the edge of very lofty roofs, 

 where it lays two eggs. Other species build in 

 concealment, as the Chimney Swallow, (H. Rustica,) 



THE CHIMNEY SWALLOW (Hirundo Rustled). 



and the Sand Martin, (H. Riparia,) while the House 

 Martin, (H. Urbica,} constructs an ingenious semi- 

 globular nest of mud beneath the eaves of houses, 

 even in the midst of our crowded streets. White's 

 monographs of these four species, (Letters xvi. xvm. 

 xix. xx. and xxi., second series,) are highly inter- 



