92 ANATOMY OF THE WOOD EAT 



The palatal ridging, situated upon the roof of the mouth 

 between the rows of the molariform teeth, consists of two 

 series of four transverse ridges, one series upon either side, 

 separated by a medial sulcus. The two pairs most craniad 

 slope partially medio-caudad. Posterior to these is a 

 slightly-defined transverse prominence running uninter- 

 ruptedly from one tooth row to the other. 



The tongue is fleshy, of moderate size, and is not ap- 

 preciably papuliferous. 



Parotid gland (fig. 5). Each of these occurs in two, 

 illy-defined divisions. The anterior one fills the angle of 

 the jaw, lying well forward over a part of the masseter with 

 one extension thrust dorsad in front of the base of the ear, 

 and another behind it. Cranio-ventrad the two parotids 

 almost meet. In this region they partly overUe the sub- 

 maxillary glands. A parotid duct leaves either gland upon 

 its medial surface several mm. (6-8) caudad of its cranial 

 border and pierces the buccinator well towards the front of 

 the mouth. The anterior margin of the posterior division 

 lies superficial to the caudal border of the anterior one. 



In Teonoma the gland, especially the posterior division, 

 is somewhat smaller and decidedly thinner, with smaller 

 lobulations. It is darker in color than in Homodontomys. 



Submaxillary gland (fig. 5). The two glands lie in con- 

 tact with each other along the median line of the throat. 

 They are partly deep to the parotids (anterior divisions) 

 and extend caudad well towards the chest. 



In Teonoma they are a trifle shorter, extending not so 

 far caudad, but broader, better defined, and probably more 

 efficient than in Homodontomys or Neotoma. In the latter 

 subgenus the parotids and submaxillaries are of the same 

 color. In Teonoma the former are the darker. 



The parotid glands secrete a liquid that is comparatively 

 non-viscid, without mucin, and rich in ptyalin, which latter 

 is especially active in the digestion of starchy foods. These 



