480 BRITISH FOSSIL REPTILES. 



with the nasal ; it then joins the malar and the prefronto-lacrymal, and descends internal 

 to the mandible to join the palatine.^ Each maxillary (?i, 21') affords alveoli for eight or 

 nine teeth. 



Tlie premaxillary is the largest of the bones of the head. The pair, by confluence or 

 connation, constitute the fore part of the upper jaw (22), expanding from a sub-obtuse 

 apex as it recedes, and preserving its entireness for an extent of about two inches. This 

 tract seems to be arched above transversely, with a slightly convex upper longitudinal 

 contour continued along the medial ray or process (22')- Of the configuration of the 

 palatal surface the specimens give no evidence. Erom the analogy of Pterodactijlus 

 Cuvieri and Pt. Sedgwichii^ we may infer that this (premaxillary) part of the 

 bony roof of the mouth was entire, and strengthened by a median ridge. The lateral or 

 alveolar borders formed alveoli for four teeth on each side. Thus the hind expansion 

 of the premaxillary divides into three rays or processes. The upper medial or nasal ray 

 is the longest : it is continued backward, continuing the initial curve of the upper 

 contour of the face as far as the nasals, tiie mid suture or confluence of which bones it 

 overlaps, and joins suturally to an extent precluding any movement of the upper jaw on 

 that part of the head. The length of this ray is about 3| inches. The pair of lower or 

 alveolar rays extend back for about I^ inches. 



The malar (26) forms the lower narrower end of the oval orbit, sending up dhe pointed 

 process (united with that of the maxillary?) toward the prefrontal, and a longer and stronger 

 one to join the postfrontal. The squamosal (27) continues the zygomatic bar backward to 

 abut against the tympanic. Its precise position and direction are left doubtful in the 

 specimens hitherto obtained, but it is unquestionably present, and contributes to the fixa- 

 tion of the tympanic. 



This (28) is a moderately long and strong pedicle, immovably articulated to the mastoid, 

 paroccipital, and squamosal ; thickest posteriorly, where it is strengthened by an 

 outer marginal ridge, sending forward and inward a process which may articulate with 

 the pterygoid (but of this I could not get clear evidence), expanding at its distal end to 

 receive the abutment of the squamosal or lower zygoma, and to form the convex condyle 

 for the articular element of the mandible. 



The dentary parts of the mandible are confluent at the symphysis, which is as long as 

 the undivided fore part of the premaxillary. The ramal part of the dentary is compressed, 

 and gains a depth of about 10 lines before it bifurcates. The alveolar border of the dentary 

 extends as far as that of the maxillary, viz. about 5 inches, beyond which the upper prong 

 (PL 17, 32') is continued above the mandibular vacuity, underlapphig the surangular (29) 

 and terminating in a point. The lower prong (ib. 32") terminates in a point before attaining 

 the vacuity ; it is underlapped by the fore part of the angular (so), with which it articulates. 



^ This description is on a liomological hypothesis, subsequently discussed (p. J86). 

 - Pterosauria, PI. 7, fig. 1 , b. 



