114 ZOOLOGICAL GARDENS. 



cere ; and a membranous expansion between the base 

 of the outer and middle toes, precluding to a certain 

 extent that power of retroverting the outer toe which 

 characterizes the Nocturnal groups of the Rapacious 

 Order. In the system of analogies they bear, as has 

 frequently been remarked, the same relationship to the 

 Cats as is borne by the Vultures to the Dogs ; but the 

 retractility of their talons, which furnishes one of the 

 strongest organic proofs of the justice of this compa- 

 rison, is of a somewhat different kind, consisting, not 

 in the withdrawing them entirely within a fold of the 

 skin, but in elevating and bending them backwards 

 over the last phalanges of the toes. In both cases, 

 however, the effect is one and the same, that of pre- 

 venting their sharp points and edges from being worn 

 down by the constant attrition to which they would 

 otherwise be exposed, and which would speeddy inca- 

 pacitate them for the important services they are 

 intended to perform. 



It is to the destructive powers of their talons that 

 the Falcon tribes are indebted for their instinctive pro- 

 pensity to make their prey of living victims ; and to the 

 firmness of their grasp that they owe an almost equally 

 characteristic trait, the habit of conveying their prey 

 through the air. But there is so much diversity in the 

 mode in which these operations are carried into effect, 

 dependent upon such striking modifications in various 

 parts of their organic structure, as to indicate clearly 

 the necessity of subdividing to a very considerable ex- 

 tent this numerous family, which in the Linnsean system 

 formed only a single genus. Much has of late years 

 been effected by different authors, and in particular by 

 MM. Savigny, Vieillot, and Cuvier, towards the attain- 

 ment of this desirable end ; but the most complete and 

 systematic view of the whole family that has yet been 



