372 DE. ST. GEORGE MITABT ON THE SKELETON OF [M.iy 7, 



while its outer margin continues on as the apex of the whole 

 sphenotie process (fig. 7, sph, p. 378). 



The external margin of that whole process, in P. erithacus, is 

 even ; no marked process projecting from it outwards and ventrad 

 in front of the ascending process of the quadrate. 



In L.flavopalUatus the sphenotie process curves a little inwards 

 towards its apex, is flattened externally and dorsally, and ventrally 

 grooved antero-posteriorly. Both the groove and the process 

 from its internal margin are, however, relatively as well as abso- 

 lutely shorter than in P. eriihacus — especially the process. A 

 marked difference between the two also exists at its outer border, 

 which, in L. flavopalliatus, sends outwards and downwards a 

 marked ecto-sphenotic process, so that the margin of the articular 

 concavity for the quadrate (which appears, in both species, at 

 the hinder end of the external border of the sphenotie process), 

 instead of being slightly marked with no definite anterior boundary, 

 as in P. erithacus, appears very marked and is sharply limited ante- 

 riorly by the ecto-sphenotic projection (see, in fig. 1, the small 

 process projecting downwards just in front of the summit of the 

 ascending process of the quadrate). 



In P. erithacus a shallow temporal fossa runs postaxiad and 

 slightly dorsad between the postorbital and sphenotie processes, 

 being bounded preaxially by a marked ridge which descends on 

 the cranial surface from the postorbital process to the inner side 

 of the root of the sphenotie process. The temporal fossa has its 

 dorsal margin defined by a slight ridge, very convex dorsad, which 

 runs postaxiad from the postorbital process. The fossa is limited 

 ventrally by another slightly marked ridge, nearly straight, or 

 only most slightly convex dorsad, which continues on postaxiad 

 the ventral margin of the sphenotie process. These two slightly 

 marked ridges meet at a point as much behind the hinder margin of 

 the auditory meatus as that meatus is broad, and at a little higher 

 level than the uppermost margin of the meatus. At the point 

 where these ridges meet there is a slight prominence which may 

 be distinguished as the postsquamosal prominence (psp). 



The auditory opening in P. erithacus is limited in front only by 

 the ascending process of the quadrate. Its postaxial margin is 

 formed by the anterior edge of the broad postmeatal bony lamella, 

 which edge, or margin, is faintly concave preaxiad at its lower 

 part, but most strongly concave preaxiad at its more dorsal 

 portion. 



The meatal opening is bounded above by a narrow bony lamina 

 which extends preaxiad and mesiad (ventrally to the outer margin 

 of the root of the sphenotie process) to bound posteriorly the cup 

 into which the outer articular surface of the head of the ascending 

 process of the quadrate fits. The inner anterior end of the 

 lamina hardly descends at all behind the process of the quadrate, 

 but a marked though short process projects outwards from its 

 middle just above the middle of the auditory opening, which 

 prominence may be distinguished as the suprameatal process («m). 



