ADAMS, PHYLOGENY OF THE JAW MUSCLES ]3l 



Capiti-mandibularis profundus (C. m. p.). 

 Pterygoideus anterior (Pt. a.). 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC GROUP 

 (INNERVATED BY VII) 



Depressor mandibulae. 



MUSCLES OF THE ADDUCTOR OR TEMPORAL GROUP 

 (INNERVATED BY V 3 ) 



Capiti-mandibularis superficialis (C. m. s.). — This slip of the eapiti- 

 mandibularis would cover the deeper fibers and arise from the quadrate, 

 squamosal and jugal and be inserted with the medius in the suprameck- 

 elian fossa. 



Capiti-mandibularis medius (C. m. m.). — This slip would arise on the 

 upper part of the skull and be attached to the parietal, squamosal, and 

 perahps to some of the bones of the otic region. It would join the rest 

 of the capiti-mandibularis in its insertion. 



Capiti-mandibularis profundus (C. m. p.). — This deep slip would arise 

 on the alisphenoid and outer face of the pterygoid and be inserted with 

 the rest of the mass on the mandible. The whole capiti-mandibularis 

 mass would probably be inserted in the suprameckelian fossa. It would 

 be attached to the bones surrounding the fossa and extend down into it, 

 after the manner of other reptiles, where the whole insertion of the capiti- 

 mandibularis is on the inside of the mandible. 



Pterygoideus anterior (Pt. a.). — This muscle was no doubt strongly 

 developed as in all typical reptiles. It arose on the under side of the 

 pterygoid and might have extended over the upper face of the pterygoid 

 region as in Chelydra. The form of the articular shows plainly that the 

 muscle must have been inserted on the ventral side of the articular, for 

 there is no evidence that it extended more than slightly into the outer 

 face of the bone. 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC GROUP 

 (INNERVATED BY VII) 



Depressor mandibular (D. m.). — This muscle was no doubt arranged 

 as in other reptiles. It arose on the parietal and extended around the 

 squamosal to be inserted on the upper face of the retroarticular process 

 of the articular, which plainly shows the marks of the insertion. 



