524 THE ANATOMY OF VERTEBKATED ANIMALS. 



masum, or Mennet stomach. This portion is comparatively 

 slender and elonguted, and its mucous membrane has a totally 

 different character from that of the other three segments, being 

 soft, highly vascular, and glandular, and raised into only a few 

 longitudinal ridges. 



It will be observed that the psalterium is so constructed as 

 to play the part of a very efficient strainer between the reticu- 

 lum and the abomasum ; nothing but very finely-divided, or 

 semi-fluid matter, being capable of traversing the interstices 

 of its lamellse. 



The gastric aperture of the oesophagus is situated at the 

 junction of the paunch and the reticulum ; the margins of its 

 opening are raised into muscular folds, and are produced, 

 parallel with one another, along the roof of the reticulum to 

 the opening which leads into the psalterium. When the lips 

 of this groove are approximated together, a canal is formed, 

 which conducts directly from the oesophagus to the psalte- 

 rium. 



A Ruminant, when feeding, crops the grass rapidly and 

 greedily, seizing it with its tongue and biting off the bundle 

 of blades thus collected, by pressing the lower incisors against 

 the callous pad formed by the gum which covers the pre- 

 maxill*. The bunches of grass are then hastily swallowed, 

 accompanied by abundant saliva. After grazing until its ap- 

 petite is satisfied, the Ruminant lies down, usually inclining 

 the body to one side, and remains quiescent for a certain space 

 of time. A sudden movement of the flanks is then observed, 

 very similar to that which might be produced by a hiccough ; 

 and careful watching of the long neck will show that some- 

 thing is, at the same time, quickly forced up the gullet into 

 the cavity of the mouth. This is a bolus of grass, which has 

 been sodden in the fluids contained in the stomach, and is re- 

 turned, saturated with them, to be masticated. In an ordinary 

 Ruminant this operation of mastication is always performed in 

 the same way. The lower jaw makes a first stroke, say in the 

 direction from left to right, while the second stroke, and all 

 those which follow it until the bolus is sufiiciently masticated, 

 take place from right to left, or in the opposite direction to 

 that of the first. While the mastication is going on, fi-esh 

 quantities of saliva are poured into the mouth, and, when the 

 grass is thoroughly ground up, the semifluid product is passed 

 back into the pharynx and swallowed once more. These 

 actions are repeated until the greater portion of the grass 

 which has been cropped is pulpified. 



