﻿WEALDEN FORMATIONS. 



3 



the temporal fossa. A flat surface of bone (8, 12), equalling the breadth of the temporal 

 opening, lies exterior to it; a narrower concave tract (11) divides the openings; the 

 posterior surface (7) is broader than the lateral ones. 



In Teleosaurus and allied genera (e. g. Metriorhynchus, Teleidosaurus, Steneosaurus, 

 Pelayosaurus, &c.) the upper temporal openings are relatively larger and the surrounding 

 flat tract of bone is of less extent than in Hylaochampsa, which herein more resembles 

 the tertiary and modern Crocodilia, although the form of the openings is teleosauroid. 



The general form of the upper cranial surface posterior to the orbits resembles, in 

 Hylaoc/tampsa, more that in Crocodilus, Metriorhynchus, and Pelayosaurus, than that in 

 Teleosaurus cadomensis and in Gavialis, in which latter the breadth exceeds the length. 



The orbits in Hylaeochampsa (PI. II, fig. 24, o) are circular and better defined by 

 the post-frontal (12) from the lateral outlets if) of the temporal fossae than in Crocodilus, 

 and herein they more resemble the orbits in Teleosaurus ; but they are less horizontal 

 than in Tel. cadomensis, and incline less to the vertical position than in Tel. (Pelayosaurus) 

 temporalis; their outline is obliquely upward and outward. The prefrontal (14) and 

 lacrymal (73) swell out a little anterior to the orbit, whence the maxillary (21) and nasals 

 (15) continue to form the upper jaw. This recalls the character of that part of the skull 

 in the Gavial rather than in the Crocodile. 



These modern or proccelian representatives of the order Crocodilia differ from the 

 Lacertilia in the greater extent or degree of ossification of the palate. 



The ' pterygo-maxillary vacuity 11 is large, and is bounded, as in Lizards (PI. II, 

 figs. 6 and 7, y), by the pterygoid (24), the ectopterygoid (25), the palatine (20), and, in most 

 genera, Iguana, e. g., by the maxillary (21). But the ' palato-maxillary ' vacuity 2 (figs. 6 

 and 7, n) between the vomer, maxillary, and palatine, does not exist in Crocodilia ; nor is 

 there a trace in that order of an ' interpalatine vacuity.' 3 The ' interpterygoid ' vacuity 

 in Lacertilia * appears to be represented by the much smaller opening which serves as 

 the ' palato-naris,' or hinder orifice of the nasal air-passages in modern Crocodilian 

 genera. 5 



In his description of the Caen Gavial (Teleosaurus cadomensis, Geof.) Cuvier indicates 

 a large vacuity, more advanced in position than the hinder nostril of modern Crocodiles, 

 and more resembling the 'interpterygoid vacuity' of Lizards (PI. II, fig. 7, s). This 

 he regarded in the Caen Gavial as the ' palato-naris.' 6 



1 See my 'Anatomy of Vertebrates,' vol. i, p. 157, fig. 98, c, y; "grand trou palatin " of Cuvier, 

 ' Ossemens Fossiles,' 4to, torn, v, pt. ii, p. 133, pi. vii, fig. 4 r; also "trou ovale assez grand," p. 259, 

 pi. xvi, fig. 3, Varanus niloticus. 



2 'Anat. of Vertebrates,' torn, cit., fig. 9S, v, n. 



3 lb., ib., fig. 98, D, m. 



4 lb., ib., fig. 98, d, s. 



5 Ib., ib., fig. 98, c, n. 



6 "La fosse nasale posterieure ;" described as " tres-grande," and marked with the letter 5 in fig. 4, 

 plate vii, 'Ossemens Fossiles,' torn. cit. 



