312 UNGULATA 
A parallel modification has also taken place in the molar teeth of 
the Proboscidea. 
As the hypsodont tooth is essentially a modification of, and, as 
it were, an improvement upon, the brachydont, it is but natural to 
expect that all intermediate forms may be met with. Even among 
the Deer themselves, as pointed out by Lartet, the most ancient 
have very short molars, and the depressions on the grinding surface 
are so shallow that the bottom is always visible ; while in the Cerzidu 
of the more recent Tertiary periods, and especially the Pleistocene 
and living species, these same cavities are so deep that whatever be 
the state of the dentition the bottom cannot be seen. Some 
existing Deer, as the Axis, are far more hypsodont than the majority 
of the family ; and, on the other hand, many of the Antelepes (as 
Tragelaphus) retain much of the brachydont character, which is, 
however, completely lost in the more modern and highly specialised 
Sheep and Oxen. 
Fic. 124.—Stomach of Ruminant opened to show internal structure. a, Gsophagus ; D, 
rumen or paunch ; ¢, reticulum or honey-comb bag; d, psalterium or many plies ; e, abomasum 
or reed; f, duodenun. 
The complicated stomach of the Pecora (Fig. 124), which is 
necessary for the performance of the peculiar function known as 
“chewing the cud”—a function common also to the Tragulina 
and Tylopoda—is divided into four well-defined compartments, 
known as (1) the Rumen or Paunch, (2) the Reticulum or Honey- 
comb Bag, (3) the Psalterium or Manyplies, (4) the Abomasum 
or Reed. The paunch is a very capacious receptacle, shaped like a 
blunted cone bent partly upon itself. Into its broader base opens 
the oesophagus or gullet at a spot not far removed from its wide 
orifice of communication with the second stomach or honey- 
comb bag. Its inner walls are nearly uniformly covered with a 
pale mucous membrane, which is beset with innumerable close-set 
short, and slender villi, resembling very much the “pile” on 
velvet The honey-comb bag is very much smaller than the paunch. 
