CHEWING THE CUD 85 1 



Species of Tragulus (smallest among living Ungulates) occur in 

 Indo-Malaya, India, and Ceylon ; one species of Dorcatherium, 

 of aquatic pig-like habits, is found on the west coast of Africa, 

 (iroup 4. — Pecora or Cotylophora — the true ruminants, including 

 deer, giraffes, cattle, and sheep. Only the third and fourth 

 digits are complete, the fused third and fourth metacarpals and 

 metatarsals form "" cannon bones." In the embryos of ox and 

 sheep, the second and fifth metacarpals and metatarsals are also 

 represented ; the second metacarpal and fifth metatarsal are 

 unstable and soon disappear ; small traces of the fifth metacarpal 

 and second metatarsal persist. The fibula is represented by a 

 small nodular bone articulating with the lower end of the tibia, 

 and forming the external malleolus. There may be in addition 

 a rudiment of the proximal end attached to the upper part of 

 the tibia, but the two parts are never united. Paired outgrowths 

 of the frontal bones are common, capped with horny sheaths in 

 the Bovida3, deciduous and restricted to the males in almost 

 all Cervidce. There are no upper incisors, and rarely upper 

 canines ; there are three pairs of lower incisors, which bite 

 against the hardened gum above ; and the lower canine resembles 

 and is in the same series as the incisors ; the typical dentition is 



^^^. The stomach has four distinct compartments. The placenta 



3133 



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 sahva. 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 papillae. Along these the food 

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

 chambers are strictly oesophageal, not stomachic. 



Cervid^ — 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. 



