LAW OF CORRELATION. 85 



into a corresponding concavity, forming a closely-fit- 

 ting joint, which gives a firm attachment to the jaw, 

 but almost restricts it to the movements of opening 

 and closing the mouth. The jaw of the carnivora de- 

 velops 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 en- 

 dued with the requisite power, extent, and freedom of 

 motion, for the wielding of these weapons. These and 

 other structures of the highly-organized carnivora are 

 so coordinated as to justify Cuvier in asserting that 

 1 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 particu- 

 lar 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 individu- 

 ally, give the teeth, or are given thereby reciprocally, 

 and, in commencing by any of these, whoever pos- 

 sesses rationally the laws of the organic economy will 

 be able to reconstruct the entire animal.' " 



" The law of correlation ' receives as striking illus- 

 trations from the structure of the herbivorous mam- 

 mals." A limb terminating in a hoof serves for loco- 



