548 



DR. C. F. SONXTAG on THE COMPARATIVE ANATOMY 



the lips, and some of its fibres fuse with those of the muscles 

 of the angle of the mouth and orbit. It covers the anterior part 

 of the masseter muscle and the facial vessels. It has been divided 

 along the lines i.i. in text-fig. 53. 



The masseter muscle (text-fig. 53) has been described by 

 Macalister. It has a tendinous lower border (&), from under 

 cover of which the facial artery (a) emerges and runs antero- 

 superiorly ; it gives off an external nasal branch (c) which runs 

 along the antero-syperior border of the cheek-pouch (CP). The 

 masseter is crossed by the anterior facial vein (fZ), transverse 

 facial artery {f), and Stensen's Duct (e). 



Text-figure 53. 



The side of the head of Phascolarctos cinereus. 

 J. Jc. posterior auricular vessels ; I. parotid gland. Other letters in text. 



Macalister has described the attolens, attrahens, and retrahens 

 muscles which act on the large auricles. 



The anterior J acial vein has the usual origin, course, relations, 

 and branches. It unites with the posterior facial vein on the 

 (Surface of the exoccipital process {g) to form the external jugular 

 vein. No part of it is seen in the interramal space of the 

 mandible, and the vena transversa (text-fig. 54, 12), which is 

 long and V-shaped, connects the external jugular veins (11) 

 instead of the antei-ior facials ; it receives lingual, muscular (3, 

 18), sub-maxillaiy (21), and a single submental vein (2), but no 

 anterior jugiblar vein connects it to the internal jugidar vein. 



The Parotid Gland is large, and forms a prominent mass in the 

 face and neck. Running on its sui'face are the posterior auricular 

 vessels. 



The neck is divided, as usual, into mesial and lateral triangles 

 by the stei'no-mastoid muscle (text-fig. 54, 10), and these have 

 the usual boundaries. The base of the lateral triangle is formed 



