THE SKULL IN THE CHAMELEONS. 97 
There is only one parietal bone (p, 7.p); this is quite distinct from the squamosals (sq), 
postero-laterally. The temporal vacuity (figs. 1, 3, & 4,/.¢.s) is a large oval space, 
with an oblique emargination in front, formed by the hinder edge of the postorbital 
(pt.o). Butin the adult skull of the Common kind (Plates XVI. and XVII.) the temporal 
space is between the interparietal within and the postorbital, squamosal, and parietal 
outside. I question whether the parietals in this species ever had a distinct inter- 
parietal; at any rate it only had a temporary existence. ‘This relatively large, knobbed 
slab of bone has an arched lateral outline, and projects backwards half its length beyond 
the foramen magnum (/.m); it has a lateral pair and a sublateral pair of rows of 
tubercles, and a median row more compressed and less distinct from each other. 
Only the fore margin of the parietal rests directly upon the membranocranium (dura 
mater) ; the main part, even over the skull, sends downwards a median keel, which rests 
upon the top of the endoskeletal crest (supraoccipital, fig. 5, s.0). 
In this species the postorbital ( pt.o) just touches the foremost outer tubercle of the 
parietal (fig. 5); from the middle of the latter (fig. 1, p, sq) a descending process bends down 
upon the fore part of the top of the squamosal: this is where ankylosis has taken place 
in the adult of the Common kind; and this outer part corresponds with the aborted 
lateral parietal of that species, which articulates with the great outer parietal crest 
behind. Here there is no such joint; it is all one bony tract. ‘The postcranial part of 
‘the common parietal bone in this species is hollow and smooth below (figs. 2 & 4, p); 
the keel is continued some distance behind the supraoccipital. 
The fore part of the roof is formed of two pairs of bones; and these only partially 
cover it; they are the nasals and prefrontals (fig. 3, 7, p.f') The nasals are united by 
a suture and are narrow behind, where they bind on to the fore spur of the frontal, and 
broad in front, where they articulate with the ascending part of the maxillaries (mz), 
not with the nasal process of the premaxillary, which does not ascend so far in this 
kind. For two thirds of their length they have the supernasal fontanelle (s.n.f) outside 
them; this is pyriform, and ends narrow behind, between the end of the frontal and 
the top of the prefrontal. 
This latter bone (p.f') is large, and covered above with large crowded bosses ; it has 
a short anterior suture with the nasal, in front of the membranous space, and an 
oblique crescentic suture with the anterior margin of the frontal. It makes part of the 
rough ornamentation of the fore face, above the maxillary (fig. 1, p.f, mx), and then, 
ascending, has both an anteorbital and a superorbital position, forming by its inner 
face the anterior fourth of the eye-socket. The postorbital (pt.o) is an arcuate bone, 
margining nearly a fourth of the eye-socket supero-posteriorly, and fixing itself to the 
contiguous bones by two pairs of snags. The upper two of these form the two rounded 
teeth of a short suture with the frontal (figs. 1 & 3); the two lower processes are 
larger, more divaricated, and oblique; the front spur descends, and is fastened inside 
