422 NORTH AMERICAN BIRDS. 



usual ; but in the Cypseliiw they are 2, 3, 3, and 3, as sliown in the accom- 

 panying cut borrowed from Dr. Sclater's masterly memoir on the Cypscliila:, 

 (l*r. Zoul. Soc. London, 1805, 5'J3), which also serves as the basis of the 

 arrangement Iiere presented. 



i^ 



Left foot of Clurtma zonaris. Left foot of PanyplUa mtlanoUuea. 



Cypselinae. Tarsi li'atlicrocl ; phalanges of the iniilclle and outer toes three 

 eaeh (instead ol' four and live). Hind toe directed either forward or to one 

 side, not bacicward. 



Tarsi feathered ; tot'sl)are; hind toe directed forward . . . Ci/pselil.l. 

 U')tli tarsi and toes feathered ; hind toe lateral .... Panyptila. 

 Ch%turin%. Tarsi bare ; phalanges ol' toes normal (four in middle toe, 

 five in outer). Hind toe directed backwards, though sometimes versatile. 

 Tarsi longer than middle toe. 

 Tail-feathers spinous. 



Shafts of tail-feathers projecting beyond the plumage . Chcetura. 

 Slial'tvs not i)rojeeting, (Xcphvecetes) .... Cijpsehides. 



Tail-feathers not s|)inous Vollocalliu. 



Tarsi shorter than middle toe Dendrochelidon. 



The Swift,s are cosmopolite, occurring througliout the globe. All tlie 

 genera enumerated above are well represented in the New World, except 

 tlie last two, wliicli are exclusively East Indian and Polynesian. Species of 

 Collovallia make the " edible bird's-nests " which are so much sought after in 

 Ciiina and Japan. Tliese are constructed entirely out of the hardened saliva 

 of tlie bird, although formerly supposed to be made of some kind of sea-weed. 

 All the C'l/jisi'luffi- liave tlie salivary glands highly develojjed, and use the secre- 

 tion to cement together the twigs or other substances of which tlie nest is con- 

 structed, as well as to attach this to its support. The eggs are always white. 



There are many interesting peculiarities connected with the modification 

 of the Cijpsclula', some of which may be briefly adverted to. Those of our 

 common Chimney Swallow will bo referred to in the proper place. Poiu/p- 

 tila sancti-hicroniimoi oi Guateniala attaches a tube some feet in le Ji to 

 the under side of an overhanging rock, constructed of the pnijpus or seed- 

 down of plants, caught Hying in the air. Entrance to this is from below, 

 and the eggs are laid on a kind of slulf near the top. Cha-twra imliura of 

 Brazil again makes a very similar tube-nest (more contracted below) out of 

 the seeds of Trixis divarimta, susj)ends it to a horizontal branch, and covers 



