GENERAL CHARACTERS OF THE VERTEBRATA. 221 
6. The bones which form the fingers proper, and which are 
known as the phalanges (Pp). 
Essentially the same parts can be traced in the hind-limb of a 
typical Vertebrate animal, but they are known by different names. 
The bones which unite the limb to the trunk are usually more 
or less completely united together, constituting a single mass, 
known as the zznominate bone (fig. 119, 7). This is followed 
by a long cylindrical bone, which forms the upper portion of the 
hind-limb, and is known as the “ thigh- 
bone,” or femur (f). Following this are 
the two bones of the shank, correspond- 
ing to the vadius and ulna of the fore- 
limb, and known as the “dza and fibula 
(¢ and s). Of these, the zdéa (¢) corre- 
sponds to the vadzus, and is mainly con- 
cerned in carrying the foot. Next comes 
a series of small bones, which form the 
ankle, and are known as the éarsus (r). 
This is succeeded by a series of cylin- 
drical bones (usually five in number), 
which form the root of the foot, and 
which are termed the metatarsus (m). 
Finally, the metatarsus is succeeded by the 
bones of the toes, which in this case are 
again termed 'the phalanges (~). In both 
limbs the usual number of phalanges to 
each toe or “ digit” is three. 
The digestive system of the Vertebrata 
does not require a lengthened notice. The 
mouth is usually furnished with éee¢h, which 
have for their chief function the reduction 
of the food to a condition in which it can _ tL 
be digested. In some animals, however, os Reciabaneag sare 
such as the snakes, the teeth are only nate bone; /'Thigh-bone, 
used to hold the prey, and not for masti- or femur; # Tibia; s 
cation ; and in others, such as the turtles et ek NESE i 
and birds, the jaws are not furnished with tarsus: p Phalanges. 
any teeth at all. The food is also usually 
subjected in the mouth to the action of a special fluid—the 
saliva—which acts chemically as well as mechanically upon 
the food, and which is secreted by special glands, known as the 
