290 



ZOOLOGY. 



tions of the knee and heel in such a way that, whilst they are 

 flexed, they act on the tendons of these muscles, and so flex 

 the toes. The weight of the body assists in this movement, 

 which enables the bird to perch without fatigue. 



Fig. 231. The Koyal Eagle. 



The differences which exist in the form of the feet of birds 

 have a reference to the mode of life and habits of the animal. 

 In the cassowary (Fig. 221) and ostrich (Fig. 232), birds as 

 rapid in running as the horse, the paws are not only robust, 

 but long, and the feet comparatively small.* In the messenger 

 (the falco serpentarius, or secretary bird), which pursues 

 serpents as his food, following them with long strides, this 

 conformation of the foot is also observed. In the eagle (Fig. 

 231), falcon, vulture, &c., these organs are not merely robust, 

 but strong, and the toes are armed with talons, large, hooked, 

 and sharp, with which they seize, tear, destroy, and carry oil' 

 their prey. Birds destined to live by the margins of rivt-rs, 

 and to hunt for worms and fishes in shallow waters, or by 



* In the original it is, " Les pattes sont non-seuli-mont ri>Mi*i-s, , n ais tri-s- 

 longues, et le pied coraparativement petit." But in the word font d>iiHl), 

 :m:it.>mists include always and in every animal the three regions of tlu> tors. 

 tarsus, and metatarsus. R. K. 



