xxviii PREFACE. 



The jaw of the Carnivore developes a plate of bone of breadth 

 and height adequate for the implantation of muscles, with power 

 to inflict a deadly bite. These muscles require a large extent of 

 surface for their origin from the cranium, with concomitant 

 strength and curvature of the zygomatic arch, and are associated 

 with a strong occipital crest and lofty dorsal spines for vigorous 

 uplifting and retraction of the head when the prey has been 

 griped. The limbs are armed with short claws, and endued with 

 the requisite power, extent, and freedom of motion, for the wield- 

 ing of these weapons. These and other structures of the highly- 

 organised Carnivore are so co-ordinated as to justify CUVIER in 

 asserting that ( the form of the tooth gives that of the condyle, of 

 the blade-bone, and of the claws, just as the equation of a curve 

 evolves all its properties ; and exactly as, in taking each property 

 by itself as the base of a particular equation, one discovers both 

 the ordinary equation and all its properties, so the claw, the 

 blade-bone, the condyle, the femur, and all the other bones in- 

 dividually, give the teeth, or are given thereby reciprocally ; and 

 in commencing by any of these, whoever possesses rationally the 

 laws of the organic economy will be able to reconstruct the entire 

 animal.' l . 



The law of correlation receives as striking illustrations from 

 the structure of the herbivorous mammal. A limb may termi- 

 nate in a thick horny hoof. Such a foot serves chiefly, almost 

 exclusively, for locomotion. It may f paw the ground,' it may 

 rub a part of the animal's hide, it may strike or kick ; but it 

 cannot grasp, seize, or tear another animal. The terminal ungu- 

 late phalanx gives, as CUVIER declares, the modifications of all 

 the bones that relate to the absence of a rotation of the fore-leg, 

 and those of the jaw and skull that relate to the mastication 

 offered by broad-crowned complex molars. 



But there are certain associated structures for the coincidence 

 of which the physiological law is unknown. f I doubt,' writes 



1 Op. cit. p. 49. 



