INSESSORES. HIRUNDO. 119 



length of bill, approaching in shape to that of some of the 

 AmpeliddE of the Dentirostral tribe. Their nidification is 

 curious, many of the genera forming the receptacle for their 

 eggs of mud or clay, others of extraneous matters, aggluti- 

 nated by a viscous liquid, provided from a glandular appa- 

 ratus peculiar to such species *. During their migratory 

 movements they fly in immense flocks, and also frequently 

 breed in large societies. 



Genus HIRUNDO, Linn. SWALLOW. 



GENERIC CHARACTERS. 



Bill short, much depressed, and wide at the base ; upper 

 mandible bent at the tip, and carinated. Gape extending as 

 far backwards as the eyes. Nostrils basal, and oblong, part- 

 ly covered by a membrane. Feet having the tarsi short, 

 toes slender, three before and one behind; the outer toe 

 united to the middle one, as far as the first joint. Tail of 

 twelve feathers, generally forked. Wings long and acumi- 

 nated, the first quill-feather being the longest. 



The species of this genus are very numerous, and are 

 spread throughout every part of the globe. Their food con- 

 sists entirely of winged insects, which they seize with great 

 dexterity during their flight. That flight is very rapid and 

 buoyant, and is supported for a long time, without visible 

 fatigue. The nidification of many of the genus is curious 

 and peculiar ; the exterior coat of the nest being compact 

 and hard, generally formed of clay, or earthy materials ; and 

 the inner part lined with feathers and other soft substances. 

 They moult but once in the year, Avhich takes place in Fe- 



* The nests of some exotic species, almost entirely formed of this vis- 

 cous matter, are highly esteemed as a condiment by the Chinese and other 

 Eastern nations. 



