SALIVARY GLANDS OF MAMMALS. 399 



omnivorous rats with ferine tendencies, the submaxillaries are 

 in excess : in most other Rodents which subsist mainly or ex- 

 clusively on vegetable products the parotids are the largest. They 

 are enormous in the Beaver, extending from before the ears 

 forward and downward to contact with the submaxillaries, which 

 are about one-twentieth their size ; the whole forming a sort of 

 glandular collar : the buccal glands are numerous. In Leporidce 

 the parotids partly inclose the base of the ear-conch and also 

 descend to meet the submaxillaries : the parotid duct crosses 

 the upper part of the masseter and terminates opposite the last 

 upper molar tooth. The submaxillary duct terminates at the 

 side of the frsenum linguae : the submaxillaries are thin and 

 long: the chief mass of the molar follicles is near the upper 

 molars. The submaxillary glands are almost as large as the 

 parotids in the Paca (Coeloye?iys): both glands are large: the 

 latter present a compact reddish tissue. There is also a large 

 zygomatic salivary gland, which exists, of smaller relative di- 

 mensions, in the Guinea-pig (Aperea). In the Hamster the 

 parotids are elongate, narrow, and applied, as in the Ornitho- 

 rhynchus, to the back of the cheek-pouches : there is also an 

 accessory lobe, beneath the masseter. The submaxillaries are 

 large, round, and of a reddish colour. The sublinguals are small, 

 subglobular. In Bathyergus the salivary glands are smaller than 

 in most other Rodents. 



Amongst Insectivora the hedgehog is remarkable for a zygo- 

 matic gland which seems to be a development of the homologue 

 of the ' molar ' glands in Marsupials. The parotids are larger 

 than the submaxillaries ; but both are well-developed. The sub- 

 lino-ual follicles are in two series, the larger one next the mandi- 



JT5 O 



bular ramus. The mole has large parotids and submaxillaries, 

 the former oblong, the latter subdivided into roundish masses : 

 the sublingual is placed very near the mandible : there is no 

 zygomatic gland. In shrews the maxillary exceeds the parotid 

 gland in size : the latter follows the auditory meatus in its in- 

 ferior position. The same proportions hold in the insectivorous 

 bats : but in the fruit-eating Pteropines the parotids are the 

 larger glands. 



o ~ 



Great is the diversity of the salivary system in the order Bruta, 

 as the difference of food and ways of getting it might indicate. 

 The parotids are somewhat less than the submaxillaries even in 

 the phyllophagous Sloths, and are much the smallest in the in- 

 sectivorous families. In the Armadillos the parotid gland is small : 

 its duct opens into the mouth near the angle of the lips. The 



