6 NATURAL HISTORY. 



and what looks like a backward turned knee in his hind leg is his heel, the true elbow and knee being 



almost hidden by the skin. 



The reason of this arrangement is seen by looking at the skeletons of the two animals. In the 

 Bear the metacarpals and metatarsah, or five long bones extending between the wrist and the 

 ankle respectively, and the joints of the toes, are kept in a horizontal position, as in ourselves ; 

 in the Lion, on the contrary, the metacarpals and metatarsals are lifted almost into a vertical 

 position, the walking surface being now afforded by the under surface of the toe-bones, or pha- 

 langes. ' By reason of this the Lion gets an extra lever in his leg, in addition to the two levers 

 which the Bear possesses, namely, those afforded by the bones of the arm and fore-arm and of the 

 thigh and leg respectively ; and consequently his springiness is greatly increased. An animal which 

 wafks like the Bear, on the sole of its foot, is said to be plantigrade : one which walks on its fingers, 

 like the Lion, Cat, or Dog, is called digitigrade. 



As in all animals in which the fore limbs are used for support, and not for prehension, the 

 collar-bone, or clavicle, is either wholly absent or quite rudimentary, and the fore limb has there- 

 fore no bony connection with the trunk, but is attached simply by muscles and ligaments. The 

 Carnivores, in leaping or running, often come down with their whole weight upon the fore legs, 

 and if a lar<*e bony clavicle, like that of a Monkey or Bat, were present, it would infallibly be 



broken. 



The bones are all strongly bound together by elastic bands, or ligaments, and are covered by the 

 great fibrous masses, or muscles, which, forming as they do the flesh, take the chief share in giving to 

 each animal its characteristic shape. These muscles are, in most instances, attached to the bones by 

 stron cords or bands resembling the ligaments, and called tendons. The bones being, in great measure, 

 articulated or jointed to one another by smooth surfaces, sometimes flat, sometimes round, sometimes 

 pulley-like, act as levers. The muscles are usually attached at one end to a fixed at the other to a 

 movable bone ; when they act, by shortening in length and widening in diameter, they make the more 

 movable bone to turn upon the other. In this way they cause the limbs to be straightened or bent, the 

 jaws to be opened or shut, the claws extended or retracted, and perform all the other movements of which 

 the animal is capable. The development of the muscles in the larger Carnivora is wonderfully great. 

 A Lion will kill an Ox with a blow of his paw, and drag it off to his lair as easily as his humble 

 relation, the Cat, disposes of a Rat or Mouse. 



We now have to consider a most important series of organs the organs of alimentation or nutri- 

 tion ; those, in fact, which serve the purposes of taking in, preparing, and digesting the food. They 

 are the mouth with its tongue, teeth, and salivary glands, the gullet, stomach, and intestines, with 

 the liver, and sweetbread, or pancreas. 



We are all familiar in ourselves with four kinds of teeth, namely (1), the " incisors," or cutting 

 teeth, in front ; (2), the " canines," the pointed eye-teeth that come next ; (3), the " false grinders," or 

 " premolars ;" and (4), the true grinders, or " molars." Man has a very even and full-mouthed series ; 

 the Carnivora, on the other hand, possess a most irregular series, and in this series there are 

 certain gaps or interspaces. Our own even orderly set is best adapted for a mixed diet, that has for 

 the most part undergone a great amount of change by cooking. But the Carnivora, in their wild 

 state, must eat flesh raw, and for the most part reeking, and this has to be torn from the conquered 

 prey. So that the teeth have to be applicable to the first, or destructive process, and then to the 

 tearing to pieces of the fleshy substance, and the scraping of the bones ; they may even have to crush 

 the bones themselves, the more spongy parts serving for food ; and, greatest feat of all, to break 

 the hardest long bones for the succulent marrow. 



The mode of feeding and the form and number of the teeth of necessity correspond : tearing and 

 gnawing are processes that need teeth like knives and scissors, while grinding or chewing require 

 teeth like millstones. Both these kinds exist in the Bear. In the Dog the crushing teeth become 

 less in size and importance ; in the Lion they are suppressed, and all the teeth have a cutting 

 character, their number being at the same time much reduced. 



The teeth are often all that remains of certain extinct creatures ; they are, therefore, a most 

 important part of the anatomy of an animal, as well as being of great service in the matter of 

 classification or grouping. They are the hardest of all the organs; their relation to the food of the 



