184 



posteriorly near the middle of the skull, and are well developed. They are 

 bounded in front by the prefrontals and ethmoid. The prefrontals are stout 

 bones, directed obliquely downward, and terminate in a large truncate articu- 

 lar face for a facet of the palatine. The ethmoid is generally wide and ter- 

 minates in an apex. It presents a large facet downward and laterally for 

 the anterior articular surface of the maxillary, opposing a corresponding facet 

 of the vomer. Anterior and exterior to this point it exhibits a lateral excava- 

 tion for the superior condyle of the premaxillary. 



Fie. 8 sjBz^ 



Rift mzM 



% 



> 



Fig. 8. — Cranium of Portheus violossus, Cope, one-fourth natural size (linear); a, supraoccipital 

 bono; b, oxoccipital ; c, basioccipital ; d, parietal; e, pterotic; /, cpiolic; y, post frontal; ft, frontal; 

 i, prefrontal ; t, ethmoid; ?, byo-niaudibular; m, metapterygoid ; n, quadrate; o, cctoptcrygoid ; p, pala- 

 tine; q, sclerotic; r, suborbital ; s, parasphenoid ; /, premaxillary ; v, maxillary ; r, accessory maxillary ; 

 tr, dentary ; x, articnlo-angular. The opercular bones are wanting. 



Viewing the cranium on the inferior aspect, the parasphenoid and vomer 

 are seen to form a stout axis, the former running well posteriorly, and fissured 

 behind for the muscular tube. Neither supports teeth in any known species. 

 Just behind the line of the orbits, the parasphenoid gives off a lateral process, 



