58 BRITISH FOSSIL REPTILES. 



relative length. Its facial part begins behind by an expanded bifurcation bounding 

 anteriorly the nostril ; in advance of which the bone gradually expands, overlapping 

 the nasal and maxillary, descending to the alveolar border to form the major part 

 of the upper jaw, and narrowing to the end. The palatal portion (Tab. XXI, fig. 1, 22), 

 long and narrow, is continued backward between the maxillary and palatine to terminate 

 in a point penetrating the palatn-naris {p n). 



The pterygoid (Tabs. XXI, XXII, fig. 1, 24) is also a bone of considerable size, 

 especially length. It begins behind by a triradiate expansion ; the outer short subquadrate 

 branch abuts against the tympanic (28) ; the upper narrower pohited ray is wedged 

 between the paroccipital (4), mastoid (g), and tympanic (28) ; the inner and longest branch is 

 broad, wedged between the paroccipital and basisphenoid, reaching with its blunt-pointed 

 end the basioccipital. In advance of this triradiate expanse the pterygoid contracts, pre- 

 senting a concave inner border, articulating with the side of the basisphenoid (5), and a 

 more concave outer border, which forms the inner one of the cavity which was occupied 

 by the gristly petrosal. As it continues to advance, the pterygoid again expands, its 

 outer border forming an angular process, to the fore part of which the ectopterygoid (25) 

 unites ; the pterygoid then extends forward and gradually inward (mesiad), decreasing in 

 breadth, and is continued as a long and narrow strip of bone in contiguity with its 

 fellow, bounding anteriorly the long interpterygoid vacuity («), articulating outwardly for 

 one half of its extent with the ectopterygoid, and for the other half with the palatine. 



The ectopterygoid (Tab. XXI, fig. 1, 25) is an elongate plate of bone, though less 

 than half the length of the pterygoid ; its rounded hind end and much of its mesial 

 margin articulate with the pterygoid, the rest with the palatine, with which it combines 

 to form the hind boundary of the palato-naris {p n). The outer margin contributes to 

 bound the pterygomaxillary vacuity (y) posterior to its junction with the maxillary, along 

 which it extends to opposite the fifth upper tooth or thereabouts, counting forwards, 

 and there terminates in a point. 



The malar (Tab. XX, fig. 1, 20) is a long and slender, moderately bent bar of bone, 

 commencing anteriorly in a point wedged between the lacrymal and maxillary, thence 

 receding to form the lower boundary of the orbit, and expanding to be partially over- 

 lapped by the postorbital bone (12'), behind which it terminates as a wedge between that 

 bone and the zygomatic. 



This bone (ib., 27) is subquadrate, its vertical equalling its longitudinal extent ; the 

 angles are more or less produced. The upper anterior one is wedged between the pro- 

 squamosal (27') and postorbital (l2x) bones; the lower anterior one underlaps the end of 

 the malar ; the front border articulates with both malar and postorbital, the upper 

 border with the prosquamosal ; the hind border is rounded and concave, forming the 

 fore part of the 'meatus auditorius extern us' (Tab. XXII, fig. 1, m) ; the hinder half of 

 the under surface of the zygomatic expands, and is slightly excavated to articulate with 

 the outer and upper part of the expanded articular end of tlie tympanic (28')- 



