126 MR. W. K. PARKER ON THE STRUCTURE AND 



roof-bones, viz. : tlie parietals and frontals, are ntnv only one yir\v {j'.p), tlie coronal 

 sutures having early disappeared. 



This double fronto-parietal tract is twice as wide over the occiput as over the orbits ; 

 its hind margin, like its front margin, is almost straight, but the edge on each side 

 uniting it with the squamosal (sq.) converges forwards, and is a roughly dentate 

 suture — this answers to the squamous suture in Man. 



Each squamosal {sq.) is a bone with a descending and retreating handle, and a 

 roughly pentagonal blade ; these are the temporal and pre-opercular regions of the 

 bone. 



The pointed fore end of the temporal plate — its postorbital projection — is united by 

 suture with the upper edge of the maxillary (fig. 3, mx.); this is a sinuous suture, and 

 behind it the edge of the squamosal rises and flxlls twice : first outside the pterygoid 

 (pg-), and then over the " annulus tympanicus," forming the ledge under and to which 

 it is attached (fig. 3). 



The preorbital rim is formed by the nasals («.), these are very lai-ge, about half the 

 size of the fronto-pai'ietals. 



In front of their concave preorbital edge they form a large descending pedate 

 process (fig. 3), which rests upon, and is united by suture with, the fore end of the 

 maxUlary, on each side. 



The median spur of each nasal is blunt, and tlie fore edge has a large round notch, 

 exposing the nasal roof (o7.h.), which is itself notched for the nostril (e.«.). 



The main roof-bones dip into the orbit (fig. 3, /.p.), forming an orbital plate. 



The arcuate premaxillaries (px.) form a divided but strong key-stone to the great 

 arch of the face ; their palatine and nasal processes are well developed and normal. 



The maxiUaries (mx.) are notched in front, where they articulate — without the inter- 

 vention of a septo-maxillary — with the premaxiUary. 



The lower dentary edge of the bone is gently arched, and the jugal process reaches 

 as far back as the tegmen tympani [t.ty.). Half the depth of the side of the skuU is 

 formed by the maxillary, whose edge is cut away below the eye, and is agtiin deeply 

 notched behind the postorbital suture ; it then becomes the rapidly lessening jugal 

 process. 



The quadrato-jugals {q.j.) are one-third the length of the maxillaries, but are only 

 the size of the jugal pi'ocesses ; they strongly bind on the lower part of the squamosal 

 (fig. 3), and are grafted largely on the quadrate, and there pass under the squamosal ; 

 this is best seen in the palatal view (fig. 2). 



That view also shows how large the palatal plate of the maxillary is, especially 

 where it is locked to the pterygo-palatine arch [pg.). 



The parasphenoid (figs. 2 and 3, pa.s.) is a large bone, and reaches to within a short 

 distance of the foramen magnum, behind, and to the beginning of the unossified 

 septum nasi in front. 



It projects by a very obtuse angle behind, its " basi-temporal wings " are broader 



