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Show 1877.] ANATOMY OF THE RUMINANTS. 3 contain an account of those parts in certain species of the Cavicornia and Cervidae (such as the stomach, liver, generative organs, and brain), which are subject to variation in the different species that I have had the opportunity of examining. The stomach of the Ruminantia, on account of its complexity, presents features of special interest. As far as the general shape and proportions of its cavities are concerned, m y observations tend to show that the relative size of the psalterium in the different genera is the only characterizing feature. In the abomasum I have not detected any variation. The rumen varies as to the shape and distribution of the villi on its mucous membrane. In most of the smaller species the folds which constrict the viscus, as well as the pouches between them, are covered internally with villi, though these are larger in the latter situations. In most of the larger species the villi are absent on the folds, and are largest in the middle of the pouches. This is specially the case in the Rusine Deer. In the Sheep and its allies they are peculiarly scattered and broad at their bases, as is also the case in Moschus. In most of the smaller species of the order they are cylindrical or flattened cylinders, as close-set as the "pile" in velvet. In Portax picta they are very elaborate, close-set, pedunculated and foliaceous. In Cervus alfredi they are flattened and expanded apically, in other words tongue-shaped, as they are in Camelopardalis giraffa. In Tetraceros subquadricornutus all the villi are flattened, broad, and rounded, absent on the folds. In Table I. column VIII., further notes on the peculiarities in the rumen will be found. The reticulum varies in the depth and size of its cells, but not to any great extent. I have not ever seen them deeper than in Cervus duvaucelii (4, inch), or shallower than in the Giraffe. In some species the cell-walls are thicker than in others, as may be seen on reference to Table I. column IX. The psalterium varies more than any other section of the stomach ; and a study of its lamina? brings to mind the septa of some of the more elaborate and fully calcified corals ; for, as in them, the laminae are of different lengths, and their arrangement is subject to definite laws. This organ may be defined as a subgiobose dilatation of the upper wall of the canal leading from the reticulum to the abomasum, the lumen of which is much reduced by the development from all but its lower wall of longitudinal villous-covered folds of its mucous lining. In size it differs greatly, being very large in the genus Bos, minute in Nannotrayus and Cephalophus. Of the laminae there are a certain number (frequently ten) of a definitely greater depth than any of their neighbours ; and these may be termed primary laminae. Between each two of these there are secondary laminae of smaller size ; and such being the case, nineteen is the average number of the two sets combined. When the organ is more complex a still shallower tertiary lamina appears on each side of each secondary one ; and there may be quaternary laminae on each side of each tertiary, on either side, again, of which there may 1* |