Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0201clau Year: 1884 316 MAMMALIA. OR 11 rangular crown has four chief prominences, which are separated by deep valleys, which are not tilled with cement, but are sometimes furnished with small accessory protuberances. The prsemolars are small, and have usually only one or two protuberances. The meta- tarsal and metacarpal bones are always ankylosed, to form a cannon bone (tig. 67(M). The Ruminant ia are characterised physiologically and anatomically by rumination and by the structure of the stomach and dent
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0201clau Year: 1884 316 MAMMALIA. OR 11 rangular crown has four chief prominences, which are separated by deep valleys, which are not tilled with cement, but are sometimes furnished with small accessory protuberances. The prsemolars are small, and have usually only one or two protuberances. The meta- tarsal and metacarpal bones are always ankylosed, to form a cannon bone (tig. 67(M). The Ruminant ia are characterised physiologically and anatomically by rumination and by the structure of the stomach and dentition which is correlated with this peculiarity. The food always consists mainly of vegetable substances, which contain only a small portion of albu- minous matter, and must, therefore, be eaten in great quantities. In this relation, the division of labour be- tween the acquisition and reception of food on the one hand, and its mastication on the other, is an advantageous arrangement, which is fore- shadowed by the structure of the stomach of other Mam- malia. The animal plucks and swallows its food while moving freely from place to place, and chews and masti- cates it when at rest. The FIG. (104. — Stomach of a Calf. S,n, Paunch or rumen ; It, Reticulum ; O, or psalter- act of rumination depends inm ; A, Abomasum or rennet stomach ; Oe, End -, • -, of oesophagus: OE, (Esophogeal groove; D, be- uPon the Complicated stl'UC- - of intestine. ture of the stomach, which II is divided into four, more rarely into three, peculiarly connected divisions (fig. 094). The superficially masticated, coarse food passes through the lateral opening of the lesophageal groove, the lips of which are separate from one another, into the first and largest division of the stomach — the , or rumen (fig. 094 Ru). Thence it passes into the small r^tlci'lnm (/<'), a small rounded appendage of the rumen, which receives its name from the net-like folds of its inner surface. Afte
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