EXPLAAATIO.N OF PLATE VIII 



Jaw muscles of a lypical bird: (Itillus 



Fiu. 1. — (t(iIIus. superficial muscles. 



The oapiti-mandibularis is divided into a superficial layer, analogous with 

 the masseter of mammals, and a deep layer, analogous witli tlie temporalis. 

 The capiti-mandibularis superficialis (C.m.s.) is attached to the quadrate. 



Fig. ■2.— (lnUi()<. 



Deep muscles after removal of the capiti-mandibularis superficialis et medius. 



The ptcrygoideus anterior (Pt. ant.) has the noi-mal reptilian relations. 

 The pterygoideus posterior (Pt. post.) perhaps is attached to the quadrate. 

 The depressor mandibulse (D.m.) is of normal reptilian type. 



Fig 3.—G<iUi(S. 



Deep muscles as seen from below. The entotympanicus (En.tij.) muscle is 

 a remnant of the adductor mass of lower vertebi-ates. The parieto-mandib- 

 ularis (Pa.m.) seems to represent a part of the depressor mandibula? of 

 reptiles. 



