62 INTESTINAL MEASUREMENTS CHAP. 
structure. It is held by Gegenbaur that this organ is the 
equivalent of the reptilian tongue, and that in the skeletal 
vestiges which it contains are to be found the equivalents of the 
hyoid skeletal cartilages which support the tongue im lizards. 
In this case the tongue of mammals is a subsequently added 
structure. ae 
The oesophagus leads from the mouth cavity to the stomach. _ 
The latter organ has commonly a distinctive shape in mammals. 
This is well shown in Man. The orifices of the oesophagus and 
intestine are somewhat approximated ; and this causes a bulging 
of the lower border of the organ, usually spoken of as the greater 
curvature. A stomach of this typical form is found in many 
orders of mammals, and is unlike the stomach in any of the 
groups of lower vertebrates in shape. Sometimes the shape of 
the organ is greatly altered: it may be drawn out, sacculated, 
or divided, as in the Ruminants and Whales, into a series of 
differentiated chambers, each of which plays some special part in 
the phenomena of digestion. 
The intestine of mammals is always long and much coiled, 
though the length and consequent degree of coiling naturally 
varies. On the whole it is perhaps safe to say that it 1s shorter 
in carnivorous than in vegetable-feeding beasts. Thus the Paca 
has an intestine of 39 inches total length, while the Cat, an 
animal of about the same size, has an intestine which is only 
36 inches long. A fish diet, however, to judge from the Seals, 
is associated with a long intestinal tract. The intestine is 
divisible in the vast majority of mammals into a small and a 
large intestine. The two are separated by a valvular constriction 
save in certain Carnivores; and in the majority of cases the 
distinction is also emphasised by the presence at the junction of 
a blindly-ending diverticulum, the caecum. This latter organ 
varies greatly in length, being very short in the Cat-tribe and 
exceedingly long in Rodents. Its size is, to some extent, de- 
pendent upon the flesh-eating or grass-eating propensities of 
the animal in which it occurs. One of the longest caeca is 
possessed by the Vulpine Phalanger, in which the organ is one- 
fifth of the length of the small imtestine; while the opposite 
extremity is reached by Felis macroscelis, which has a smail 
intestine one hundred times the leneth of the caecum, 
An interesting point In connexion with the gut of mammals 
