758 MAMMALIA. 
is cotyledonary, the villi occurring on a number of distinct 
patches. . 
The process of rumination or chewing the cud cannot be understood 
without considering the complex stomach. It is divided into four 
chambers,—the paunch or rumen, the honeycomb-bag or reticulum, the 
many-plies or psalterium, the reed or abomasum. The swallowed food 
passes into the capacious paunch, the walls of which are beset with 
close-set villi resembling velvet pile. After the food has been softened 
in the paunch, it is regurgitated into the mouth, where it is chewed 
over again and mixed with more saliva. Swallowed a second time, 
the food passes not into the paunch, but along a muscular groove on 
the upper wall of the globular honeycomb-bag into the third chamber 
or many-plies. The honeycomb-bag owes its name to the hexagonal 
pattern formed by the mucous membrane on its walls. The many- 
plies or psalterium is a filter, its lining membrane being raised into 
numerous leaf-like folds covered with papille. Along these the food 
passes to the reed, which secretes the gastric juice. The first three 
chambers are strictly oesophageal, not stomachic. 
Cervidee—the widely distributed deer, absent only from the Ethiopian 
and Australian regions. The second and fifth digits are usually 
represented, often along with the distal parts of the correspond- 
ing metacarpals and metatarsals. The upper canines are usually 
present in both sexes. The horns, if present, are antlers, de- 
ciduous, and usually confined to the males. .In the reindeer, 
they are possessed. by both sexes. They are outgrowths of the 
frontal bones, are covered during growth by vascular skin—the 
velvet—and attain each year to a certain limit of growth. After 
the breeding season the blood supply ceases, the velvet dies off, 
and an annular absorption occurs near the base. Then the 
antlers are shed, leaving a stump, from which a fresh but larger 
growth takes place in the next year. The earliest (Lower 
Miocene) deer had no antlers, thus resembling young stags of 
the first year ; the Middle Miocene deer had simple antlers, with 
not more than two branches, thus resembling two-year-old stags. 
Thus there is a parallelism between the history of the race and 
the individual development. 
Examples.—Cervas, most Old World deer; Rangéfer, the rein- 
deer; ‘Adces, the elk or moose; Capreolus, the roe-deer ; 
Hydropotes, the water-deer, without antlers; A/oschus, the 
musk-deer, without antlers, with long sharp upper canines 
and large musk glands in the males. 
Giraffidee, represented by the giraffe (Grraffa camelopardalis), a tall 
Ethiopian animal, notable for its enormously elongated cervical 
vertebra, and for its long limbs. It is gregarious in its habits, 
and feeds on the leaves of trees. The lateral digits are entirely 
absent. The dental formula is ae In both sexes there are 
on the forehead short erect prominences, over the union of 
parietals and frontals, which arise from two distinct centres of 
ossification, but afterwards fuse with the skull. In front of 
these there is a median protuberance. The Okapi (Ofafia), 
