Digestive System Special. 75 



small in proportion to the animal ; but the duct, about eleven inches 

 in length and half a line in diameter, is perhaps the longest duct, 

 in proportion to the size of the animal, in the animal kingdom.* 



Marsupialia. In the Great Kangaroo the Parotid is very large, 

 extending from below the auditory meatus three or four inches 

 down the neck : in the Potoroos it reaches as far as the clavicle : 

 but in both is separated from the Sub-Maxillary. 



Monotremata. In Ornithorhyncus the Parotid is divided into 

 flat lobes, thinly applied to the fundus of the cheek pouch {ef. Cri- 

 cetus, Rodentia). 



The Sub -Maxillary Gland. 



Sectorialia. This Gland in the Dog is large and globose. 



Perissodactyla. These Glands are about one fourth of the size of 

 the Parotids, by which they are covered. 



Cete bolt their food, and have no such Glands ; except the Balaeni- 

 dae, in which they are present in a diffused form. 



In-Enamellata. Those which have long tongues (e.g. Myrmeco- 

 phaga, Dasypus,) have a hladder superadded to this Gland, both 

 for storing up the quantity of secretion needed in a sudden excess 

 of outflow in lubricating the tongue, and also for increasing the 

 tenacity of the secretion so poured out by the absorption of some of 

 the serous part of the saliva during its detention therein. 



Monotremata. In the Echidna this Gland is of unusual dimensions ; 

 it extends from the meatus auditorius along the neck, and upon the 

 anterior part of the thorax. The duct subdivides and dilates when 

 it reaches the interspace of the lower jaw; serving the same end as 

 the pyriform bladder of some In-Enamellata [vide supra). This 

 modification of * Wharton's duct' appears to be unique.* 



11. The Teeth. 



Bimana. Structure. All the teeth are 'simplices' s. obducti : 

 the coronal Cement is of extreme tenuity, seldom so thick as to 

 show a bone cell. The Dentine is 'unvascular' {i.e. the tubules 

 are not large enough to admit capillary vessels with red blood 

 corpuscles). Replacement. The * Deciduous' series consists of 



.2.2 1.1 2.2 

 ^2T2'^ni'^2T2 = 20. 



* Owen, 



