390 ON THE ANATOMY OF THE RUMINANTS. 
The stomach of the Ruminantia, on account of its complexity, pre- 
sents features of special interest. As far as the general shape and 
proportions of its cavities are concerned, my 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 
eylinders, as close-set as the “pile” in velvet. In Portaw 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. (pp. 392, 3), further notes on 
the peculiarities in the rumen will be found. 
The reticulum varies in the depth and size of its onl but not to any 
great extent. I have not ever seen them deeper than in Cervus 
duvaucelli (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 lamine brings to mind the septa of some of the 
more elaborate and fully calcified corals ; for, as in them, the laminz 
are of different lengths, and their arrangement is subject to definite 
laws. 
This organ may be defined as a subglobose 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 
Nannotragus and Cephalophus. 
Of the laminz there are a certain number (frequently ten) of a 
definitely greater depth than any of their neighbours; and these may. 
be termed primary lamine. Between each two of these there are 
secondary laminee 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 
