20 



CYPSELID^ 



very short; feet weak, small and usually pamprodactylous [i.e., all 

 four toes anteriorly directed) ; tail of ten feathers only (this latter 

 character an easily recognisable distinction from the Swallows with 

 a tail always of twelve feathers) ; palate segithognathous, no 



Fig. 12. — Wing of Cypselus africamis. x \. 



Fig. 13. — Foot of Cypselus africanus. x t- 



caecan or semitendinosus muscle. The Swifts are all birds of strong 

 flight and lay elongated white eggs in nests which are partly or 

 wholly composed of the inspissated secretion of the salivary glands. 



The range of the family extends all over the world except the 

 extreme northern and southern regions. 



Ke^j of the Genera. 



A. Tar sns feathered ; tail normal. 



a. All the toes directed forward at equal intervals Cyx:)selus, p. 21. 

 h. Toes in pairs, the third and fourth outwards, 



the first and second inwards Tachornis, p. 28. 



B. Tarsus unfeathered ; tail with the shafts stiffened 



and projecting as spines beyond the webs of 



the feathers Clicetura,Y>- 29. 



