52 COMPARATIVE ANATOMY. 



Small intestine long, of greater extent in herbivorous than 

 carnivorous animals; villi present; numerous filiform, villi- 

 bearing process in Rhinoceros. No valvulse conniventes in 

 Carnivora. Caecum small and simple in carnivorous, large 

 or compound in herbivorous mammals, as in Ruminantia 

 and Rodentia. Furnished with two simple cseca as in Myr- 

 mecophaga (ant-eater), or with single bifurcated spiral ap- 

 pendage, as in Hyrax (cony). Vermiform appendix is the 

 rudiment of caecum ; seen only in Phascolomys (wombat), 

 anthropoid apes and man. 



Salivary glands not present in Cetacea. Pancreas always 

 present, commonly divided into two lobes. Liver divided 

 into many lobes in the Carnivora. It is small and but little 

 divided in those having a compound stomach. The liver of 

 Quadrumana closely resembles that of man. Gall-bladder 

 generally present; absent in Equus (horse), Eiephas (elephant), 

 and carnivorous Cetacea; double in Giraffa (giraffe). Bile 

 may flow directly into the gall-bladder, as in the ox; but com- 

 monly the hepatic duct is joined by the cystic duct forming 

 the ductus communis, as in man. Adventitious intestinal 

 products occasionally met with, such are tappen, from bear, 

 during hybernation; ambergris from whale; bezoars from 

 goat and deer; phosphatic and calcareous calculi from horse; 

 felt-balls from paunch, and occasionally 'honeycomb' of 

 ox, etc. 



VIII. 



CIECULATOEY AND EESHEATOEY SYSTEMS, 



CIRCULATION is the movement of nutritive fluids of animals 

 in fixed directions, and, for the most part, within a peculiar 

 apparatus. 



The object of a circulation is twofold 



(1) To convey from an assimilative surface nutritive ele- 

 ments, and distribute them through the tissues. 



