28 



ANATOMY OF THE WOOD RAT 



ental surface of this aponeurosis. Insertion is upon both 

 the lateral and medial surfaces of the ventral border of 

 the angular process. 



In Neotoma this division is a trifle broader in its anterior 

 portion. In Teonoma the cranial border extends shghtly 

 farther forward, and the insertional portion extends farther 

 mediad. 



Pars zygomaticus (figs. 5, 6, 7, 23, 24, 25) whose deeper 

 cranial borders blend somewhat with the adjoining ones 



I 



■mas.TcvaLj.wferaod)' 



PRROTID DUCT 



Fig. 5. Head of Homodontomys, showing the more superficial glands 

 and certain muscles. (Ear cartilage cut.) 



of the next part (major), have origin from the ventro- 

 lateral border of that portion of the zygomatic arch which 

 lies caudad to the masseter major. It is inserted upon 

 the whole of the angular process of the mandible save its 

 extreme ventral border. 



Pars major (figs. 5, 6, 7, 23, 24, 25) arises by three 

 heads — the (a) ectal, (6) ental and (c) infraorbital. 



(a) The ectal head arises upon the superior portion of 

 the septum and anterior border of the maxillary root of 

 the zygomatic arch, extending caudad to within a couple 

 of millimeters of the jugal. Insertion is upon the mas- 

 seteric ridge of the mandible. 



