DIGESTIVE SYSTEM. 51 



much thicker than in the other chamber moderately so in 

 rapacious markedly so in granivorous birds. In the latter 

 the epithelium forms two thick plates for the trituration or 

 food. Hairy concretions found in gizzard of Cuculus (cuckoo). 

 Intestine small and large, small, folded several times upon 

 itself; large, straight, with commonly two caeca, one on 

 either side; terminates in a cloaca. 



Salivary glands present: pancreas generally with more 

 than a single duct. Liver almost always divided into two 

 lobes; gall bladder wanting in few birds. 



Mammalia. Gullet narrow, with thick walls. Stomach 

 either simple, constricted, sacculated, or compound. Simple 

 in Carnivora and man, when it is pyriform, the base being at 

 cardiac, and apex at pyloric end ; constricted in Equus (horse), 

 defining cardiac from pyloric extremity; sacculated in Pho- 

 ccena (porpoise), and Rodentia, where the constriction is car- 

 ried so far as nearly to divide the stomach into distinct cham- 

 bers. Such division is actually attained in Pteropus (frugivo- 

 rous bat), in which two, and in Macropus (kangaroo), and 

 Semnopithecus (douc monkey), with whom three divisions are 

 seen, each of which in their turn may possess a tendency to 

 sacculation, the last constriction recalling the form of large 

 intestine. In Ruminantia the stomach is compound and 

 divided into four peculiar chambers. First, paunch (rumen), 

 much larger than the others, with thin walls, and furnished 

 upon its inner surface with horny papillae; second, honey- 

 comb (reticulum, 'hood'), smaller, lies on the right of pre- 

 ceding and is lined with deep four-, five-, or six-sided cells; 

 third, many-plies (psalterium, omasum, 'book'), the smallest, 

 is of a sub-globular form, and furnished with a number of 

 deep, longitudinal lamellae of mucous membrane, which are 

 closely approximated : fourth, the true stomach (abomasum, 

 'reed'), which resembles in form the human stomach; the 

 mucous membrane is sparsely plicated longitudinally. With 

 the Camelidae, the many-plies is wanting, and the paunch is 

 without papillae, while a reticulated structure resembling 

 that of the honeycomb is seen at its fundus. 



Peculiar gastric gland met with in Phascolomys (wombat) 

 and Rodentia. 



