No. 2304. REPTILIAN CHARACTERS IN 2IAMMALS--W0RTMAN. 



backwards underneath t]ie prominent and flaring edge of the orbital 

 cavity. At the posterior end of the maxillary, commencing above the 

 anterior border of the second molar, is the unusually prominent 

 masseteric ridge, wliich extends backwards on the underside of the 

 jugal arch as far as the back of the orbit. Tlie frontals entering into 

 the formation of tlie top of the skuJl are unusually broad ; they reach 

 their greatest breadth where they join the laclii'ymals near the ante- 

 rior border of the orbit, and terminate in front in pointed extremities 

 which are received between the nasals and premaxillaries. Behind 

 they articulate v/ith the parietals by a gently curved suture, whose 



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^stO. 



Fig. 2.— Rynchocyon petersi. 



Qm. J., quadratojugal; Sq., squamosal. 



IN FIG. 1.) 



X 2. (Other letters as 



concavity is directed forwards, and upon the upper border of the eye 

 cavity they are deeply notched. 



The parietals, like the frontals, have an unusual breadtli and are 

 rather short from before backwards; they articulate in front witli the 

 frontals and beliind with the occipital, quite in the usual way in the 

 mammahan skull. There is a short inconspicuous sagittal crest, from 

 the anterior end of which diverge two faint ridges passing almost 

 directly outwards to the tips of the postorbital processes. These 

 ridges, together with the occipital crest behind, are of importance as 

 marking the area of attachment of the temporal muscle, and serve 

 to delimit rather sharply the temporal area, of wliich more will be said 

 later. The outstanding featm'e of the parietals is that they are pro- 

 duced upon either side into strong depending processes, which furnish 

 the upper posterior boundary of the orbital cavity. The presence of 

 a postorbital process is not unusual in the skull of the mammal, but 



