Fig. 7. — Right side of the shall of Ornithorhynchus, shoving separate 

 postfrontal and prefrontal bones and the malar hone. ( X 2.) 



SO =. Supra-occipital. 

 EO = Ex-occipital. 



C = Occipital condyle. 

 SQ = Squamosal. 

 F = Supra-articular foramen. 

 A = Articulation for the lower 

 jaw. 

 AS = Alisphenoid. 

 Pt.F = Postfrontal. 



O = Orbit osphenoid, 



P = Palatine. 



L = Lachrymal. 

 PF = Prefrontal. 

 FR = Frontal. 



N = Nasal. 

 inx = Maxillary. 



J) = Dental horuy plate. 



M == Malar bone. 



Fig. 3. — Occipital aspect of the skull of Ornithorhynchus. ( x 2.) 



SQ = Squamosal bone. 

 SO = Supra-occipital. 

 PAR = Parietal. 



fm — Foramen magnum. 

 BO = Basi-occipital. 

 EO = Ex-occipital condyle. 

 F = Supra-articular foramen. 



[The transverse imperfect divisions in the supra-articular foramina are of 

 uncertain significance.] 



