THE EVEN-TOED UNGULATES 357 



other creature. The tusks are enormous, particularly those in the 

 lower jaw, which are curved upwards. 



The true Swine, the Peccaries, and Hippopotami form but 

 a small division of the Cloven-hoofed or Even-toed Ungulates, by 

 far the greater number being included in a group familiarly known 

 as the Ruminata, because, as part of the digestive process, they 

 " chew the cud." To quote Professor A. H. Garrod : " As to the 

 details of the process, the individual, a cow, for instance, whilst 

 grazing, nips off the grass between the large cutting teeth in the 

 front of the lower jaw and the tough pad which replaces in these 

 creatures the similarly-situated teeth of the upper jaw. After each 

 mouthful it does not proceed to masticate the food, but swallows 

 it forthwith, and continues thus to graze until it has satisfied its 

 appetite. Seeking a quiet and shaded spot, it then seats itself 

 that it may ruminate, or chew the cud, at leisure. If watched, it 

 will be seen that it commences shortly to perform a slight hiccough 

 action, in which some contraction of the flanks is to be noticed. 

 Its mouth, which was previously empty, is found to be full of what 

 it is not difficult to recognise to be coarsely-masticated grass, 

 which has been forced up into it ; and this it immediately proceeds 

 to chew between its back or grinding teeth, in a slow and con- 

 tinuous manner, moving its lower jaw uniformly from one side 

 to the other. When this chewing process has lasted for a time 

 sufficient to convert the food into a pulpy state, it is again swal- 

 lowed, after which another bolus is brought up to undergo a 

 similar operation. And this is repeated at frequent intervals until 

 most of the food swallowed has been masticated." A complicated 

 stomach is necessary for the production of this elaborate chewing 

 process, and this organ, as found in the ox, is divided into four 

 well-defined chambers or compartments, viz. : (i) the rumen, 

 or paunch ; (2) the reticulum, or honeycomb bag (so called from 

 the peculiar arrangement of the ridges on the mucous membrane 

 which lines it) ; (3) the psalterium, or many plies ; l and (4) the 

 abomasum, or reed, which is the stomach proper. 



The Chevrotains (Tragulina), or Deerlets, are undoubtedly 

 the most ancient of the Ruminata, and stand as a connecting- 

 link between the swine and the true ruminants. They are all 



1 So called on account of the longitudinal folds, like the leaves of a book, with 

 which the lining membrane is raised. 



