XL] THE ALIMENTARY SYSTEM. 437 



side, in front of the ear, behind the ramus of the lower jaw, 

 and in front of the mastoid process resting on the styloid 

 process and muscles. It gives off a tube, or duct, which runs 

 forward outside the masseter muscle, and then turns inwards, 

 piercing the buccinator muscle and cheek, so as to open 

 into the mouth opposite the second upper premolar. (2) The 

 sub-maxillary glands are next in size, and one on each side is 

 placed within the lower part of the mandible and above the 

 digastric muscle. Its duct runs forward and opens (close 

 to its fellow of the opposite side) beside the fold of skin 

 which attaches the under surface of the tongue to the flooi cf 



Fie .371. A DISSECTION OF THE RIGHT SIDE OF THE FACE. 

 a, the sublingual ; b, the submaxillary glands, with their ducts opening beside the 

 tongue in the Hoor of the mouth at d ; c, the parotid gland and its duct, which 

 opens on the siaa of the cheek at e. 



the mouth. (3^ The sub-lingual glands are still smaller, and 

 are placed in the floor of the mouth, between the tongue and 

 the gum of the tower jaw. They open by numerous minute 

 ducts. 



Besides these considerable structures, the mucous mem- 

 brane which lines the mouth is beset with minute buccal 

 glands. 



5. On extending our view over man's sub-kingdom, we see 

 that salivary glands may be entirely absent, as is the case in 

 most Fishes, in Crocodiles, and in the Cetacea. Only in man's 

 class do we find definite glands of all the three kinds above 

 described, though very generally salivary glandular structures 



