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 honey comb -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 papillae. Along these the food 

 passes to the reed, which secretes the gastric juice. The first three 

 chambers are strictly cesophageal, not stomachic. 

 Cervidae 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. Cervus^ most Old World deer ; Rangifer> the rein- 

 deer ; Alcesy the elk or moose; Capreolus, the roe-deer; 

 HydropoteSy the water-deer, without antlers ; Moschus, the 

 musk-deer, without antlers, with long sharp upper canines 

 and large musk glands in the males. 



Giraffidse, represented by the giraffe (Giraffa camelopardalts], a tall 

 Ethiopian animal, notable for its enormously elongated cervical 

 vertebrae, and for its 1 ong limbs. It is gregarious in its habits, 

 and feeds on the leaves of trees. The lateral digits are entirely 

 absent. The dental formula is < 2223. 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 (Okapid), 



