﻿BIRDS OP PREY. HARPAGUS. 299 



nunculus of Dr. Horsfield. For the present, however, 

 we shall consider all these variations from the typical 

 structure as sectional groups ; the more so, because 

 deviations, equally marked, exist among the Thamno- 

 phelince, or bush shrikes, another group of predatory 

 birds, although belonging to the Dentirostres. Now, as 

 these modifications occur in closely connected species, 

 and of the same countries, it is quite clear that they do 

 not characterise either natural or geographic groups ; in 

 other words, that they are aberrant species, and not sub- 

 ( generic. 



(245.) The next principal type of Fako appears 

 to be that of Bidens of Spix (which we discovered in 

 Brazil previous to that traveller), but which name has 

 been properly changed for Harpagus. In this the 

 wings are less pointed than in Falco, but not so rounded 

 as in the hawks ; the bill has a peculiar thickness, and 

 instead of one very strong tooth in the upper mandible, 

 there are two smaller ones ; the structure of the feet 

 accords with that of the generality of true falcons, but 

 the scutellation of the tarsi are very different : instead 

 of numerous small scales, disposed in a reticulated or 

 net-like manner, those in front of the tarsus are large, 

 broad, and transverse. The passage between Harpagus 

 and Falco is marked by a well known and beautiful 

 little bird, the Falco ccerulescens of Linnaeus, which we 

 class as an aberrant Harpagus, with which it agrees in 

 having a doubly toothed bill, united with the more 

 pointed wings of the subgenus Falco. This species, not 

 now before us, does not appear to be otherwise different 

 from Harpagus; for, by the description we quote from *, 

 the tarsi appear to be similar to those of the typical 

 species, all of which inhabit Brazil. The third sub- 

 genus is represented by a most beautiful crested falcon 

 from India, the Falco lophotesf, of which only one 

 specimen, now in the Paris Museum, is known. Like 

 the latter, the bill of this also is bidentate; but the feet 



* Zoological Journal, vol. i. p. 328. 

 f Temminck, Planches Color^es, pL 10. 



