GENERAL CHARACTERISTICS. 



131 



Both bones of the lower limbs are always 

 present and distinct. Those of the wrist and 

 ankle, as well as of the metacarpus and meta- 

 tarsus (the bones corresponding to those of 

 the palm of the hand and the sole of the foot), 

 are also quite distinct, and in general can be 

 moved about pretty freely among each other. 

 The toes are free, often connected only by a 

 swimming-web, and are armed with sharp 

 hooked claws, which in the burrowing and 

 climbing species are long and powerful, in 

 the runners shorter and blunter, and in the 

 Felida and many of the Viverrida are really 

 terrible weapons. In these last forms they 

 are capable of being retracted along with the 

 last joint of the toe within membranous 

 sheaths or folds of the skin on the upper 

 surface of the foot. In this manner they are 

 protected from being worn away in walking, 

 while they can be protruded at will by means 

 of powerful muscles whenever the animal 

 wishes to put them to their natural use as 

 razor- like cutting instruments. They thus 

 form even more dangerous weapons than the 

 teeth. 



The mode in which the limbs are held in 

 walking is very various, and serves as a 

 means of distinguishing the larger sub- 

 divisions. 



The massive and rather clumsy Carnivora, 

 such as the bears, for example, place the 

 entire sole of the foot as far as the ankle on 

 the ground. The impression of their feet, 

 their tread, somewhat resembles that of man 

 or the Simiae. These are the "sole-walkers" 

 (Plantigrada). Those forms, on the other 

 hand, which have more flexible limbs and 

 more slender bodies, such as the cats and 

 dogs, place only the ends of their toes on the 

 ground; the whole weight of their body rests 

 in walking on the joint between the second 

 and the last of the small bones of the toes. 

 These are " finger -walkers " (Digitigrada). 

 Between these two extremes there are many 

 intermediate grades. The martens, for ex- 

 ample, place the whole length of their toes 



and the metacarpal or metatarsal region on 

 the ground, keeping only the ankle (or wrist) 

 elevated; they have consequently been called 

 Semiplantigrada. Most of the Viverrida, on 

 the other hand, are Semiplantigrada which 

 keep the metacarpus and metatarsus also 

 elevated. These finer distinctions, however, 

 are all the less capable of being maintained 

 since some species are semiplantigrade in 

 front, and completely plantigrade behind. 

 Naturalists have accordingly only retained 

 the designations for the structures adapted to 

 the very different modes of progression at 

 the two extremes. The plantigrade form 

 was without doubt the original mode of pro- 

 gression of the primitive carnivores; only 

 gradually have the ankle, the metacarpus (or 

 metatarsus), and lastly, the first two joints of 

 the toes been raised above the ground. 



In most cases the feet have five free toes. 

 The number may, however, sink to four 

 either on one or both pairs of limbs. But 

 the reduction is carried no further. Among 

 the carnivores we know no forms, such as 

 are found in many other orders, having feet 

 with three or two toes, or even with only 

 one. 



The dentition is even more characteristic 

 than the structure of the foot. It is dis- 

 tinguished first of all by the remarkable 

 constancy in the number of the teeth, which 

 are all placed in the front portion of the 

 jaws. With the exception of a single 

 species, the sea- otter (Enhydra), all the 

 Carnivora have in each half of the jaw both 

 above and below three incisors and one 

 canine. The only variations are in the 

 number of the molars and premolars. The 

 small close-set vertical incisors have, for the 

 most part, chisel-shaped crowns, and are 

 admirably adapted for gnawing bones. The 

 crowns are frequently so notched that the 

 series has the appearance of a saw. The 

 middle incisors are the first to appear, and 

 the outer ones the last. 



The canines, sometimes simply conical and 



