380 THE ANATOMY OP VERTEBKATED ANIMALS. 



it that of Mamjplies. The fourth segment of the stomach, 

 or second subdivision of the pyloric moiety, is termed the 

 Abomasum, or Rennet stomach. This portion is compara- 

 tively slender and elongated, and its mucous membrane has 

 a totally different chai-acter from that of the other three 

 segments, being soft, highly vascular, and glandular, and 

 raised into only a few longitudinal ridges. 



It -mil be observed that the psalteriiim is so constructed 

 as to play the part of a very efficient strainer between the 

 reticulum and the abomasum; nothing but veiy finely 

 divided, or semi-fluid matter, being capable of traversing 

 the interstices of its lameUse. 



The gastric apertm-e 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 pro- 

 duced, parallel with one another, along the roof of the 

 reticulum to the opening which leads into the psalterium. 

 When the lips of this gi-oove are approximated together, 

 a canal is fonned, which conducts directly from the oeso- 

 phagus to the psalterium. 



A Ruminant, when feeding, crops the grass rapidly and 

 gi-eedily, 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-masillae. The bunches of grass are then hastily 

 swallowed, accompanied by abundant saliva. After grazing 

 until its appetite is satisfied, the Ruminant Kes 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 obsei-ved, veiy similar to that which might be produced 

 by a hiccough ; and careful watching of the long neck wiU 

 show that something 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 sto- 

 mach, and is returned, saturated with them, to be masticated. 

 In an ordinary Riiminant 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 



