FROM THE LOWER LIAS OE CHARM OTJTH. 



445 



other skulls, however, as continuations of the squamosals, though 

 apparently divided from them by suture. Owen calls them " supra- 

 mastoids and they may correspond to Parker's " second supra- 

 temporals," though, as they lie exterior to the squamosals and not 

 beneath them, our term " suprasquamosal" is perhaps best retained. 



The articular end of the quadrate lies much below the general 

 level of the upper jaw (over an inch). This is a character not found 

 in Agamidae or most Lacertilia ; but it occurs in Iguana and the 

 Chameleons. 



The Lower Jaw. — This, which has the usual reptilian composition, 

 is 20*35 inches long from end to end ; posterior to the symphysis its 

 surface is smoothly striated by longitudinal thread-like ridges, the 

 external expression of its fibrous structure ; in front, past the pos- 

 terior end of the symphysis the surface is much roughened, and 

 along the alveolar margin finely wrinkled *. The length of the 

 symphysis is 3*35 inches; the height of the jaw from the top of the 

 coronary to the lower margin of the ramus is 3 inches. 



In the following Table are given the more important measure- 

 ments of the skull : — 



inches. 



Anterior extremity of prsemaxilla to posterior margin of parietal 18 



,, anterior margin of orbit 10 



„ „ posterior margin of orbit 130 



„ „ left nostril ...... 8*2 



„ „ „ right nostril ... 9 2 

 „ „ foramen parietale 13 



Vertical height of orbit j ¥^ 21 



Highest point of parietal to lower margin of lower jaw j g 3 



Anterior end of dentary to posterior margin of articulation with quadrate 1975 

 „ „ posterior end of articulare 21 



Section across the Skull. — The skull has been broken across in 

 several places, so as to afford a view of its internal structure ; but 

 very little is clearly displayed, except in the most posterior fracture, 

 which traverses the supratemporal fossae (fig. 1, p. 446). 



A large and originally bilaterally symmetrical mass of bone is 

 seen in the middle of the section above the lower jaw ; the greater 

 part of it consists probably of the basisphenoid ; it is channelled in 

 the middle line above by a deep narrow groove, through which a 

 line can be drawn to the middle point of the inferior concave margin 

 opposite, dividing it into nearly symmetrical halves ; the right moiety, 

 having apparently suffered but slightly from compression, is better 

 fitted for study than the left, which is much crushed together. The 

 right half is divided by a deep lateral excavation into an upper and a 

 lower portion : the latter, descending outwards and downwards, soon 

 bifurcates ; and the upper of the two processes so produced, after 

 diminishing to a narrow neck, widens suddenly into a triangular 



* The wrinkled appearance here referred to is very similar to that exhibited 

 by parts of the integument described on page 466. 



