THE SKULL IN THE CHAMELEONS. 97 



There is only one parietal bone {p, i.p); this is quite distinct from the squamosals {sq), 

 postero-laterally. The temporal vacuity (figs. 1, 3, & 4, ^. t. s) is a large oval space, 

 with an oblique eraargination in front, formed by the hinder edge of the postorbital 

 {pt.o). But in 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.o). 



In this species the postorbital {pt.o) just touches the foremost outer tubercle of the 

 parietal (fig. 3); from the middle of the latter (fig. l,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 hoUow and smooth below (figs. 2 & 4, ^j) ; 

 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, n,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 {ma:), 

 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. l,p.f, nia;), 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 



