. An introduction to the study of mammals living and extinct. Mammals. 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 ivith. Even among the Deer themselves, as pointed out by Lartet, the most ancient have very short molars, and the depressions on the grinding sm-face are so shallow that the bottom is always visible ; while in the Ccriidw of the more recent Tertiary periods,
. An introduction to the study of mammals living and extinct. Mammals. 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 ivith. Even among the Deer themselves, as pointed out by Lartet, the most ancient have very short molars, and the depressions on the grinding sm-face are so shallow that the bottom is always visible ; while in the Ccriidw 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 Antekpes (as Tragelaplms) retain much of the brachydont character, which is, however, completely lost in the more modern and highly specialised Sheep and Oxen. "\ii. Fig. 124.—Stomach of Euminaut opened to show internal structure, a, CEsophagus ; h, rumen or paunch ; c, reticulum or honey-comb bag; d, psalterium or mauyplies; c, ahomas'um or reed; /, duodenum. 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 Eeticulum 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 honev- comb bag. Its inner walls are nearly uniformly covered with "a pale mucous membrane, which is beset with innume
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Keywords: ., bookauthorly, bookcentury1800, bookdecade1890, booksubjectmammals
