84 ANNALS NEW YORK ACADEMY OF SCIENCES 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC GROUP 

 {INNERVATED BY VII) 



Depressor mandibulEe (E. and W.). 



MUSCLES OF THE ADDUCTOR OR TEMPORAL GROUP 

 (INNERVATED BY V^) 



Capiti-niandibularis superficialis. — This muscle is divided into two 

 parts by Ecker and Wiedersheim and called by them masseter major and 

 masseter minor. It seems to be a muscle representing the superficial part 

 of the capiti-mandibularis mass and may represent the two portions, as 

 it is divided in the reptiles in this paper. 



{a) Pars major. — This arises by two heads, one from the zygomatic 

 process of the squamosal and the other from the lower quadrant of the 

 tympanic annulus. It is inserted on the upper edge and outer side of the 

 mandible and serves to tighten the ear-drum, thus acting as a tensor 

 tympani. 



(5) Pars minor. — This is smaller than the major and posterior to it. 

 It is double-headed also, arising from the anterior border of the posterior 

 arm of the squamosal and from the lateral knob of the quadratojugal. It 

 is inserted on the mandible, posterior to the major. It is much shorter 

 than the major. 



Capiti-mandibularis profundus (Pterygoideus of E. and AV.). — This is 

 posterior to the eye and is covered by the pterygoideus anterior (tem- 

 poralis of E. and W.). It originates on the fronto-parietal and prootic 

 and is inserted on the coronoid process, just posterior to the insertion of 

 the pterygoideus anterior (Temporalis). 



Pterygoideus anterior (Temporal of E. and W.). — This is a large 

 muscle that fills most of the space between the prootic and the eyes. It 

 curves around the annulus of the ear, covering the capiti-mandibularis 

 profundus and going under the pars major of the capiti-mandibularis 

 superficialis. It is a double-headed muscle, one head arising on the ridge 

 between the prootic and the fronto-parietal, while the second head, aris- 

 ing on the anterior edge of the posterior limb of the squamosal, joins the 

 first and is inserted on the coronoid process of the mandible. I call it 

 pterygoideus anterior because it appears to be homologous with a muscle 

 of the same name in the Eeptilia. 



MUSCLES OF THE DEPRESSOR OR DIGASTRIC GROUP 

 (INNERVATED BY VII) 



Depressor mandibular (Ecker and Wiedersheim). — The depressor of the 

 jaw is a large muscle that covers the posterior part of the skull, overlap- 



