1044 
PROFESSOR OWEN ON SOME REMAINS OF THE 
of the broad or thick superorbital boundary, which may indicate the share which the 
frontal (n) contributed to form, with the pre- and post-frontals ( 12 ), that part of the 
orbital frame. The latter cranial element is indicated by the subangular prominence 
(ib., 12 ) at the hind part of the boundary. The dimensions of the orbit are 2 inches 
in vertical, 2^ inches in longitudinal, diameter. These relatively small cavities open 
upon the anterior third part of the skull—perhaps on the anterior fourth were the 
skull entire. 
The side-wall of the skull (Plate 38, fig. 1, 26 , 27 ), behind the orbit extending back 
beneath the horn-core (e), is vertical and (apparently has been) entire, descending from 
the base of the horn-core (c) for an extent of 5 inches. Beneath the core ( e ) is a low 
prominence ; behind this part, and below the base of the core ( b ), is a natural vacuity 
(ib., fig. 1, /), of a vertically oval form, 1 inch 11 lines in that diameter, and apparently 
1 inch 6 lines from before backward. This vacuity leads to the temporal fossa, which 
is entirely roofed over by the broad arched external cranial platform, developing and 
supporting the lateral (“ supra-temporal,” b, c ) and supei'ior (“ supra-parietal,’’ f ) pairs 
of horn-cores. 
The side-wall descends below the vertical temporal opening for an extent of 2 inches 
10 lines. The outer surface of this part is slightly convex, and sculptured by some 
vascular channels ; it is bounded behind by a shallow groove, 9 lines across, extending 
from the temporal opening obliquely downward and backward. The groove is bounded 
behind by a small rugged mamilloid process (s). 
The above-described “side-wall” holds the place of a malo-squamosal zygoma ( 26 , 27 ); 
the hinder terminal tuberosity (ib., s) I regard as part of the mastoid. 
On the left side of the skull a bony plate is continued from part of the inner 
circumference of the vertical temporal aperture for some distance transversely mesiad. 
The hinder part of this production is much thicker than the fore part, and extends 
further before ending in a broken surface : it was, probably, continuous with the 
proper parietes of the brain-case, of which, however, no trace remains. 
The major part of the extensive horn-supporting plates seems to correspond with 
those parts of the parietals and mastoids in Clielone, which make the vaulted roof of 
the temporal fossae. 
Of the tympanies, or supporting bones of the tympanic membrane in Chelonia, and 
of the articular surfaces for those bones, there is no preserved trace. 
Turning to the under surface of the present cranial specimen, the fore boundary of 
each “ palatonaris” (Plate 38, fig. 3, pn) is preserved. The roof of the mouth extends 
forward 2 inches from these boundaries. On this palatal part of a broad upper jaw, 
formed, as it seems, by the coalesced premaxillary and maxillaries, projects the 
trenchant ridge (ib. ib., r), extending nearly, but not quite, parallel with the outer 
margin (ib. ib., 21 , 22 ); it is somewhat sharper than that margin, from which it is 
divided by a pretty deep regular channel, widening from 6 lines in breadth at the mid¬ 
line of the mouth to 9 lines at its outer, best preserved, end. Behind the second ridge 
