400 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
to the articulation of the lower jaw, and is nearly covered by the 
squamosal, I would homologize it with the Stegocephalian quadrato- 
jugal. 
Temporal Region of Reptilia. 
In following out the modifications of the temporal region in the 
Reptilia I have endeavored to trace them according to the lines of 
descent, adopting for this purpose the ideas of Cope (’96) as modified 
Fig. E. — Lateral view of the skull of Pariotichus aguti, after Cope, ’95. «/., 
jugal; Pa., parietal; Pf., postfrontal; Po., postorbital; Qj., quadrato- 
jugal; Sq., squamosal; St., supratemporal. 
Fig. F. — Lateral view of the skull of Procolophon, from the restoration by 
Woodward. F., frontal; J., jugal; L., lachrymal; Mx., maxillary; 
N., nasal; Pa., parietal; Pf., prefrontal; Pmx., premaxillary; Po., postor- 
bital; Prf., prefrontal; Qj., quadratojugal; Sq., squamosal; St., supra¬ 
temporal. 
by Williston (: 04) except that I am not ready to trace the mammals 
through the Theriodontia. 
