ADAMS, PHYLOGENY OF THE JAW MUSCLES 99 



(a) Capiti-mandibularis superficialis (C. m. s.) = Masseter portion. 

 Arises on the quadratojugal, squamosal and quadrate. 



(h) Capiti-mandibularis medius (C. m. m.) — This is the inner part 

 of the temporal sheet arising on postfrontal, prootic, squamosal and quad- 

 rate under the fibers of the outer or masseteric portion. These two slips 

 arc not separate. 



(c) Capiti-mandibularis profundus (C. m. p.). — The deeper portion 

 of the mass. It arises on the parietal and is inserted on the coronoid 

 along with the rest of the capiti-mandibularis. (A lower part of this 

 muscle arises from the columella cranii and is considered as pterygoideus 

 posterior. ) 



Pterygoideus anterior (Pt. a.). — This muscle arises on the whole outer 

 surface of the pterygoid (except the branch to the palatine) and is in- 

 serted on the posterior part of the jaw. 



Ptenjf/oideus posterior (Pt. p.). — This with the exception of the lowest 

 part arises on the columella cranii and is inserted on the mandible, 

 posterior to the insertion of the capiti-mandibularis profundus. 



Pteri/go-parietalis (Pt. par.). — This muscle is peculiar to reptiles with 

 a rodlike columella cranii. It arises on the downward projection of the 

 parietal and is inserted on the whole upper surface of the pterygoid, im- 

 mediately in front of the articulation with the columella. It seems to 

 represent a part of the inner layer of capiti-mandibularis profundus that 

 separated oft' for the service of the pterygoid. The same might be said 

 of the muscle following. 



Pteryqo-splrenoidalis posterior. — This muscle arises on the basisphe- 

 noid below the gasserian notch and is inserted on the upper and lower 

 surface of the pterygoid for its whole length to a level of the articulation 

 of the basipterygoid process of the sphenoid and the pterygoid. It pulls 

 the pterygoid upward and backward. This may represent a lower slip 

 from the capiti-mandibularis profundus. 



MUSCLES OF THE DEPRESSOR. OR DIGASTRIC GROUP 

 (IXXERVATED BY VII) 



Depressor mandibulce (D. m.). — It arises on the parietal and nuchal 

 fascia and is inserted in the end of the mandible. 



AVES 



GALLIJS 

 Plate VIII, Figs. 1, 2. .3 



The musculature of the bird, Gallus, follows in most particulars that 

 of reptiles. It offers one of the most convincing items of evidence that 



