534 BRITISH FOSSIL REPTILES. 



Teleosaurus cadomensis, and with that called "grand vide palatine" or "trou palatine 

 posterieur " by Eudes-Deslongchamps in Teleosaurus teiiqmralis [Felagosaurus typus) ; 

 consequently with those which I have termed ' pterygo-maxillary ' and symbolised by the 

 letter y in my ' Anatomy of Vertebrates/ loc. cit. The vacuities in the interspace between 

 the two 'pterygo-maxillary' ones, bounded externally by the pterygoids and palatines, 

 answer to the " fosse nasale posterieure " of Cuvier in Teleosaurus cadomensis} and to the 

 " grande fosse pterygoidienne, qui limite en avant les arriere-narines " of Eudes- 

 Deslongchamps in Teleosaurus temporalis f" consequently, also, to that which I have called 

 ' interpterygoid ' and symbolised by the letter s in I(juana? 



It is plain that the palatal or posterior opening of the nasal passages offers no 

 trustworthy homological character in Beptilia. It is anteriorly situated in Clielonia and 

 Lacertilia, where those passages are vertical or nearly so; it is at the hindmost part of 

 the bony palate in modern Crocodiles, and in a more advanced position, though still in the 

 hinder half of the palate, in the mesozoic or ' amphicoelian ' Crocodiles. In each of these 

 cases it has a distinct anatomical conformation. In Chelonia and most Lacertilia [Varanus, 

 e.g.) its boundary includes parts of the vomer (13), palatine (20), and maxillary (21)/ 

 in Iguana it includes, with the same bones, also a part of the premaxillary ; in Crocodilus 

 proper it is wholly surrounded by the pterygoids ; in Teleosaurus the palatines combine 

 with the pterygoids to complete it anteriorly. 



With regard to the opening answering to the hinder nostril in Teleosaurus, we find 

 in Varanus that the halves of the divided vomer also contribute to boimd or form the pointed 

 anterior prolongation of the vacuity,^ in the formation of which, as the pterygoids take 

 the most constant and always the chief share in Lacertilia and Chelonia, and as the 

 vacuity so bounded does not in these reptiles serve as the hinder or palatal opening of the 

 nostrils, the term ' interpterygoid ' appeared to me to be most conveniently applicable. 



In the skull of the Varanus niloticus figured by Cuvier^ the presphenoid is prolonged 

 so as to seem to divide the ' interpterygoid vacuity ' into a pair ; the point of the bone, 

 however, in nature inclines upward, and does not join anteriorly either the palatine or 

 vomerine bones. In the larger monitor {Varanus indicus) and in Iguana the presphenoid 

 (PI. 60, figs. 6 and 7, 9) has a like relation to the interpterygoid vacuity (ib., «), but is not 

 so far produced. 



Von Meyer, in his figure of the base of the skull of Belodon Kapffi"' represents the 

 interpterygoid vacuity as divided by a longitudinal production, apparently, of the 

 pterygoids, the lateral parts or plates of which form with the palatines the outer border 



1 Tom. cit. 



^ ' Notes Pal^ontologiques,' 8vo, 1S69, p. 146, pis. ix — xxiv, vi. 



3 Op. cit., fig. 98, D. 



* Op. cit., fig. 98, B. 



5 Cuvier, torn, cit., pi. xvi, fig. S, &c. &;c. '' lb., ib. 



1 ' Palseontographica,' zehnter Baud, pi. xxxii, p. 227 (18C3). 



