44 MAEINB EEPTILES OE THE OXEOED CLAT. 



The palatal surface of the skull is formed mainly by the vomers (v.), palatines {pal.), 

 pterygoids (pt.), and parasphenoid (pas.). The vomers (v.) are very large bones, 

 extending nearly half the total length of the skull. Anteriorly they run in between the 

 premaxilla? to about the level of the fourth premaxillary tooth, where they terminate 

 in a point. Prom the premaxilla? to the anterior angle of the internal nares they 

 unite externally with the maxilla? ; at the internal nares, of which they form the 

 inner edge, they are somewhat narrowed, but behind these openings they again widen 

 out and terminate in a fan-shaped expansion ; immediately behind the nares they 

 probably unite externally for a short distance with the maxilla?, then with the anterior 

 end of the palatines, and in the middle with the anterior ends of the pterygoids, which 

 thus exclude the palatines from the middle line. 



The form and relations of the palatines (pal., PI. IV. fig. 1) are not well shown in 

 any specimen now available for examination. In my former paper on a skull of this 

 species (Ann. Mag. Nat. Hist. [6] vol. xvi. (1895) p. 247) these bones were described as 

 follows: — "The palatines are bounded externally by the maxilla?, internally by the 

 internal nares, of which they form the postero-external margin, and, to the greatest 

 extent, by the pterygoids. In no specimen is the whole of the posterior border 

 preserved, but its inner portion unites with the anterior edge of the lateral wing of 

 the pterygoid in a straight suture running nearly at right angles to the long axis of the 

 skull, while the outer portion seems to have joined the transpalatine, there having 

 been no suborbital vacuity in front of this bone, or, at any rate, only a small one." 

 I am not now quite certain whether the palatines actually do form part of the border 

 of the internal nares (i.nar.), or whether they are shut out from them by the union of 

 the vomers and maxilla?, which would thus alone inclose the openings. These are 

 elongated slits three or four centimetres long and about one centimetre wide. They are 

 situated about opposite the seventh to the tenth maxillary teeth and are considerably 

 further forwards than the external nares (nar.). 



The pterygoids (pt., PI. IV. fig. 1), the largest bones in the palate, are very complex in 

 form. They are triradiate, as usual in this group ; the anterior ramus joins the vomer 

 at its anterior end, where also, for some distance, it joins its fellow in the middle line ; 

 further back there is a narrow anterior interpterygoid vacuity (a.p.v.), which was not 

 noted in my former description. Behind this opening the bones again meet in the 

 middle line for a short distance and are then separated by the anterior end of the 

 parasphenoid (pas.), which is thrust between them and to a considerable extent 

 concealed by their overlap on to its palatal surface. The lateral wing of the 

 pterygoid unites in front with the palatine in a transverse suture as above described ; 

 externally it joins the transpalatine (t.p.) in a V-shaped suture, the posterior limb of 

 which passes through the prominent boss of bone which projects down from the palate 

 and terminates in an oblique flattened and roughened surface; a similar and similarly 

 constituted structure is found in many reptiles, e. g. Hatteria. The posterior border of 



