1^2 MR. W. K. PARKER ON THE STRUCTURE AND 



extent, axially; three-fifths of this is taken up by tlie huge, very diverging, widely 

 pedate, thyro-hyals {t.lnj.). 



The posterior lateral lobes are normal ; the anterior are small, in-egiilar lobes. 



In this skull the roofing and outer walls are in harmony with the inner parts of the 

 building ; the bones are very solid, and theii' outer surface is almost Ganoid, beino- 

 richly sculptiu-ed with honeycombings and clear granules, hke the. surface of a large 

 thick-walled Glohigerina hulloides. 



The roof in this old male is one bone, its parietal region projects as a thick triangular 

 process over the archway of the occiput, and the nasal end (n.) reaches to the verge of 

 the bony prenasal (figs. 5 and 7, n.px., elh.) ; there it ends in two broad, rounded lobes, 

 divided by a sharp notch — all that remains of the nasal suture. This bilobate eiid of 

 the roof is formed by the nasals, which were very large whilst distinct ; they form a 

 right and left wing over and down the antorbital region ; this part is of gi'eat breadth, 

 quite unlike the usual spike that articulates with the maxiUary. There is a regularly 

 crescentic orbital margin to the frontal region, right and left ; then a short, stout, 

 postorbital process; then a rounded notch in the temporal region (belonging to the 

 parietaLs) ; and then an oblique, crenate margin up to the terminal spike. 



This large, completely anchylosed, convex slab of sculptured bone (fig. 5) overhangs 

 (he flat orbital edge of the endocraniuni, its width, in the orbital region, increasing 

 from before backwards, whilst the inner skull, in that part, increases from behind, 

 forwards (fig. 6). 



The only part of the slab which articulates with other investing bones is the nasal 

 wing — right and left ; much of the extended ear-mass divides the parietal edge from 

 the squamosal (sq.), and the nasal lobes do not reach the nasal processes of the pre- 

 maxillaries (figs. 5 and 7). 



The jxxrasphenoid (fig. 6,pa.s.) is large and typical; the blade is sub-carinate and 

 trough-like ; the guards, on each side, are also hollow above, and receive the eai--masses 

 into their hollows ; they bend downwards, right and left, in accordance with the 

 dipping of the hind floor of the skull, towards the suspensoria (fig. 8). The handle 

 of the parasphenoid is short and bifid ; it does not reach to the edge of the base, 

 behind. 



The vomers (fig. 6, v.) are curious foot-shaped bones, and are extremely solid, 

 especially the dentigerous " toe" — an oblique, oval mass, looking straight towards its 

 fellow, from which it is separated by a space half the width of the lobe. The " heel" 

 of this bone lies over the internal nostril (i.n.), from thence it becomes a thick wedge 

 reaching to the junction of the premaxillary with the maxillary. 



The solid dentigerous lobe of each vomer, and the internal nostrils, form together a 

 transverse series of long ovals, broken by the exposed base of the girdle-bone, and 

 bounded by the bony palatines. 



The premaxillai'ies (px.) are strong, wide, have a small flat palatine, and a large 

 bowed sul)-vertical nasal process (fig. 7, n.j>x.), which overlaps the inner and upper labial 



