THREE UNPUBLISHED PAPERS BY BLYTH. 301 



but are solely insectivorous, whereas the Trochiliclce subsisting 

 partly on the nectar of flowers (though still chiefly insectivorous, 

 and pursuing minute insects on the wing as well as picking them 

 from flowers), have the bill and tongue modified accordingly.* 

 Externally, they are readily distinguishable from the Swallows by 

 having ten tail-feathers only (like the Trochilidce, and also the 

 CaprimulgidcB) : the wings are longer, narrower, and distinctly 

 curved, with very robust stems to the outer primaries, the second 

 of which equals or exceeds the first in length ; t the character of 

 the plumage is diff'erent, and each clothing feather (as in the two 

 preceding families) is furnished with a distinct supplementary 

 plumelet ; the conformation generally is much more robust ; 

 and the bill is quite of a difi'erent form, more approximating that 

 of Caprimulgus : the feet (excepting in MacrojJteryx, and perhaps 

 Atticora ?) difi"er remarkably from those of every other bird 

 known, in the circumstance of the four toes consisting each of a 

 single phalanx, additional to the unguinal phalanx which is 

 armed with a very strong, compressed, and acutely pointed claw ; 

 the representative of the hind toe is directed inward (as in 

 Caprimulgus), but with rotation of the joint forward in Cypselus 

 (whence this genus has been commonly described to have all four 

 toes directed forwards), and backward in Acanthylis and Collo- 

 calia, wherein the hind toe can be well opposed to the other toes. 

 In MacTopteryx, however, the number of joints of the toes suc- 

 cessively increases as in other birds,! and the hind toe is fixedly 

 opposed to the others. With a wide gape (as in Caprimidgus), 

 the cleft extending to beneath the middle of the eye, and always 

 quite smooth or devoid of vibrissce, the bill is minute, and com- 

 pressed anteriorly to the nostrils, having the upper mandible 

 incurved and the tomise of both inflected ; the nareal orifices are 

 exposed and vertical, forming oblique, oblong-oval slits. The 



* The Trochilidce further differ from the Cypselidce in having complex 

 vocal muscles ; though it appears that even in this respect the Patagona 

 gigas accords with the Swifts. These two families further differ remarkably 

 in theu' mode of flight. 



f In the more powerful species the first and second primaries are sub- 

 equal ; in the weaker the first is shorter. The stems of the outer primaries 

 attain their maximum strength throughout the class in certain Trochilidce, 

 known as the Sabre-wings {Campylopterus). 



\ We have seen a shght exception in Caprimulgus. 



