ALIMENTARY CANAL OF ARTIODACTYLA. 473 



the first and second cavities, and, drawing that of the psalterium, 

 ib. d, nearer to the gullet, conduct the remasticated bolus into' 

 the third cavity, the deep parallel crescentic folds of the lining 

 membrane of which occupy almost its whole area : the thick epi- 

 thelium is continued upon these folds. In the psalterium of the 

 Giraffe, between each two narrow folds there is alternately one of 

 great and one of moderate breadth, as in the Ox : l these lamellae 

 are beset with short pyriform papillae. The bolus is squeezed into 

 the interspaces, deprived of the superfluous alkaline fluid, and is 

 passed on in a less dilute state to undergo the action of the true 

 digestive acid secretion of the fourth and last compartment, ib. e. 

 The communication between this cavity and the psalterium is 

 wider than between the latter and the oesophageal groove : but 

 the distinction is marked by the abrupt termination of the thick 

 epithelium. The vascular and finely villous lining of the abomasus 

 is usually thrown into large oblique wavy rugae ; which subside 

 toward the pylorus. In the Giraffe these rugae are slightly de- 

 veloped and chiefly longitudinal: the pylorus is protected by a 

 valvular protuberance placed above it, as in other Ruminants, just 

 within the stomach ; this protuberance is relatively smaller than 

 in the Llama. 



When the Giraffe ruminates, it masticates the bolus for about 

 fifty seconds, applying to it from forty to fifty movements of the 

 lower jaw, and then swallows it : after an interval of three or 

 four seconds a second bolus is regurgitated. A slight contraction 

 of the abdominal parietes accompanies the action of the stomach 

 by which the regurgitation is commenced. This action of the 

 abdominal parietes in rumination is much stronger in the Camel. 

 The Camelidae differ from the true Ruminants in the mode in 

 which the cud is chewed; it is ground alternately in opposite 

 directions from side to side : in Oxen, Sheep, Antelopes, and 

 Deer, the lower jaw is ground against the upper by a uniform 

 rotatory motion : the movements may be from right to left, or 

 from left to right, but they are never regularly alternate through- 

 out the masticatory process as in the Camels. 



In the sucking Ruminants the first and second cavities of the 

 stomach are relatively small, collapsed, and the milk flows almost 

 wholly, at once, into the psalterium and abomasus. The laminae 

 of the psalterium are early developed in the fcetal calf. 



In all Artiodactyles the duodenum is dilated at its commence- 

 ment : it there forms a distinct pouch in the Camel. The gut 



1 In this ruminant Daubenton counted 24 large folds, and each interspace included 

 one middle sized and two small folds, ninety-six in all. ccxxii", tome iv. p. 494. 



