8o THE ADVENTURES OF 



and scan the horizon with their yellow eyes, their subtle sense of 

 smell enables them to catch the effluvia of the putrefied matter 

 on which they feed." 



In some of the towns of Mexico the black vultures are so 

 numerous — living there, as they do, almost tame in the streets — 

 that our young companion was well acquainted with these birds; 

 but he had never been present at one of their joint meals. The 

 sight of their bare, black, and wrinkled necks, plunged into the 

 body of the animal, made him almost ill. 



"Poh ! — what disgusting birds ! " — he cried. 



" You are wrong," I said ; " the birds are only obeying the 

 instinct implanted in them. Henceforward you will understand 

 better the name of the ' rapacious order,' or ' birds of prey,' 

 which is given by naturalists to vultures, eagles, falcons, and 

 owls. You are aware that the science which describes the habits 

 of birds is called ornithology. Cuvier, the great classiiier, divides 

 the feathered tribe into six orders — birds of prey, passerines, 

 climbers, gallinaceans, wading, and web-footed birds. In order 

 to prevent confusion, the orders have been subdivided into fami- 

 lies, the families into groups, the groups into genera, and the 

 genera into species. 



" How are they all to be recognised 1 " 



" By the study of certain special characteristics, which serve as 

 distinguishing marks. Birds of prey, for instance, have curved 

 beaks and claws, legs feathered either to the knee or down to the 

 foot, three toes in front, and one behind; also, the back and 

 inside toe are stronger than the others. The vultures which you 

 are looking at, the only birds of the order which live in flocks, 

 belong to the Cathartus genus."* 



" Look ! there are some which keep at a distance. They look 

 as if they were afraid." 



"No; they have gorged themselves, and are now digesting 

 their meal ; unless danger compel them to take flight, they will 

 remain motionless until sunset." 



* From the Greek KadapTiis, "that which purifies." In fact, this bird 

 assists in cleansing the streets in towns where there is no organisation for the 

 purpose. 



