72 Mammalia. Digestive System. 



Monotremata. The dorsum of the Tongue in Echidna is broad, 

 flat, callous, and beset with hard papillae (representing in these lowly 

 organised Mammals the lingual teeth of Fishes), between which and 

 the palatal spines {supra 6) insects are crushed. The conical pro- 

 cesses on the Tongue of Ornithorhyncus may also subserve the same 

 purpose. 



10. Salivary Glands. 



Ratio of their development. 



Cheiroptera. In the Insect-eating Bats the Maxillary exceeds 

 the Parotid gland in size : but in the fruit-eating Pteropines the 

 Parotids are the larger glands. 



Rodentia. In the Omnivorous Eats with ferine tendencies, the 

 Submaxillaries are in excess : in most other Rodents, which subsist 

 mainly or exclusively on vegetable products, the Parotids are the 

 largest. 



Marsupialia. The proportions of the Parotid and Submaxillary 

 difi'er according to the nature of the food, as in Rodentia. 



- The Parotid Gland. 



Rodentia. In Castor (Beaver) the Parotids are enormous, extend- 

 ing from before the ears, forward and downward, to meet the Sub- 

 maxillaries (which are about one-twentieth their size), the whole 

 forming a sort of glandular collar. A similar development is found 

 in the Leporidse. In Cricetus (Hamster) the Parotids are applied to 

 the back of the cheek pouches. 



Sectorialia. In the Seal tribe the Parotid is either very small or 

 wanting. In the Dog it is comparatively small ; relatively larger 

 in the Cat ; and more so in the Bear tribe. 



Proloscidia. The salivary glands are all largely developed. 



Perissodactyla. In the Horse the Parotid forms a considerable 

 mass, extending from its normal position behind the Masseter up- 

 wards to the Ear Conch, the base of which it embraces, and down- 

 wards to the Larynx, where it meets its fellow. 



Artiodactyla. The Parotids are large in all Ruminantia. 



Cete. In the Piscivorous Cete, which bolt their food like Pishes, 

 the Parotids are absent. 



Sirenia. The Parotids are large (the species of this Order 

 browze on fuci). 



In-Fnamellata. In the Great Ant-Eater the Parotid gland is 



