370 Mr. Vigors's Sketches in Ornithology/. 



forms. The species are as yet too ill defined to enable us to ex- 

 tricate them from the confusion into which our ignorance of their 

 variations in plumage according to age and sex has involved them ; 

 while the usual deficiency of subjects for examination which the 

 British student has sa frequently cause to lament, equally serves 

 to exclude all pretensions to accuracy in the details of the family. 

 I shall therefore only venture to point out those well known forms 

 which afford us certain grounds for observation. 



It may be in general observed that in the higher latitudes, 

 where an inferiour degree of heat does not demand the same rapid 

 decomposition of animal substance as in the warmer climates, the 

 process of destruction, as far as it involves animal agency, is com* 

 paratively speaking slow and gradual, and is carried on by those 

 weaker agents, who, as I before observed, by their numbers only 

 counterbalance their inferiority in size. When on the other hand 

 a more powerful influence of the sun calls for a more instantaneous 

 removal of offensive matter, the same work is performed by agents 

 of greater powers and more rapid execution. It is in such tro- 

 pical climates that the Vultures are chiefly observed to exist ; 

 chiefly I say, as although they are sometimes found in higher 

 latitudes, and particularly some of the aberrant species of the 

 family, it is within the tropicks that they abound in the fullest 

 numbers, and with the most extensive powers. There they may 

 be noticed as performing a conspicuous part. Their food is 

 chiefly animal substance in a decaying state,* and their business 

 in nature is to clear away with rapidity that mass of putrifying 

 matter, which, if left to a more gradual course of decomposition, 

 would be the forerunner of pestilence and death. 



* This mode of feeding draws a marked line of distinction between the pre- 

 sent family and that of the Falconidce ; the latter preying only on living ani- 

 mals. These habits thus distinguishing the two groups, were not unnoticed 

 by the ancients. '' ot yvirss^^^ says Plutarch, ^' evi rocs oj-^xs ruf 

 ^isp^o^oruy aufAxruv (^s^ovrxiy rojv ^t ytx^x^uv y.xi vyixivovruv a/aS'ijo-zv ovk 



s;^8<r<v." De cap. ex hostib. utilit. Tom. VI. p. 324. Ed. Reiske. 



" ti^Evos ocitrzrxi \_yv\f'\ ^uvros^ aS* xttoktivvvj-iv E/x-Nl^y^^ov a^sv, us xsroi Kxt 

 t£§xx.e5 KXi XX vvKTivo(jt,x' ^fV)<T^xi Js Tois xhKois xiTQ^xvHaivJ''' QuaBstiones 



