GENERA L CHA RA C TERIS TICS 



tibia, occupying the inner side of the limb, corresponds to the radius of the fore-arm, 

 while the smaller outer bone, or fibula, represents the ulna. The ankle, or tarsus, 

 corresponds to the carpus in the fore-limb, and likewise consists of two transverse rows 

 of small bones. Two bones of the uppermost row, viz. , the calcaneum, or heel-bone, 

 and the astragalus or ankle-bone, are specially modified. In the foot proper the 

 bones correspond with those of the hand ; those representing the metacarpais 

 being, however, termed metatarsals. It will 

 frequently be found convenient to speak of 

 the extremity of the fore-limb, or hand, as 

 the manus ; while the hind foot may be termed 

 the pes. 



In the foregoing summary we have spoken 

 of the hand and foot as consisting of five 

 fingers and toes, or digits; and this is the 

 case with most Monkeys, many Carnivores, 

 Rodents, etc. In other cases, however, and es- 

 pecially among the Hoofed Mammals or Un- 

 gulates, there is a tendency to the reduction of 

 the number of digits. Thus in the cattle and 

 deer, commonly known as Ruminants, the num- 

 ber of functional digits is reduced to two, cor- 

 responding to the third and fourth of the typ- 

 ical series of five ; while in the horse only a 

 single digit remains, which in the fore-limb cor- 

 responds to the middle or third finger of the 

 human hand, and in the hind-limb to the 

 middle toe. 

 Arrangement Almost all Mammals when adult 



of the have both jaws provided with a 



Teeth series of teeth, varying greatly in 

 number and structure in the different groups. 

 These teeth are almost invariably fixed in 

 separate sockets ; and while the front teeth have 

 but a single root or fang, the side- or cheek- 

 teeth very generally have two or more such 

 roots, each of which occupies a separate divi- 

 sion of the socket. In all cases the teeth are 

 fixed in their sockets merely by the aid of soft 

 tissues connected with the gum, and are never 

 welded to the jaws by a deposit of bone. Very 



generally there is a sharply-marked line of division, termed the neck, between the 

 root, or portion of the tooth implanted in the jaw, and the crown or exposed 

 portion. 



In most of those Mammals, in which the teeth of different parts of the jaw 

 differ in structure from one another, there are two distinct sets of teeth developed 



HUMAN SKELETON. 



