OPHTII ALMOSAUE CJS. 



21 



concave, for union with the posterior limb of the maxilla. The jugal formed the 

 whole of the ventral and the lower part of the posterior border of the orbit. 



The upper part of the posterior border of the orbit is formed by the long curved 

 postorhital (text-fig. 8, C), the lower end of which widens out a little and overlaps 

 the outer face of the upper portion of the jugal. Above this the bone bears on its 

 inner face a surface for union with the up)per end of the quadrato-jugal, and above this 

 again its upper face is overlapped first by the supratemporal, then by the postfrontal. 

 In this upper region the outer surface bears a prominent ridge, which forms the actual 

 rim of the orbit. 



Right lachrymal of OpMhalmosaunis : A, inner side; B, outer side. (R. 21S0, |- nat. size.) 



jii.f., facet for jugal ; mx.f., facet for maxilla ; iiar.h., border of external nares ; n.f., facet for nasal ; 

 orb.r., rim of orbit ; jor.f., facet for prefrontal. 



The laclirymal (text-fig. 11) is an irregularly triangular bone, with the posterior 

 angle produced backwards into a process, of which the ventral surface is raised 

 into a strong ridge internally and a deep groove externally (ju-f.), both fitting 

 on to corresponding surfaces on the upper side of the anterior end of the jugal. Tlie 

 upper border of this process is continued backwards and upwards on to the outer face 



