﻿WEALDEN FORMATIONS. 5 



extent of 6 lines ; a tract of matrix of 3 lines extent intervenes between the super- 

 occipital, which here shows a jagged upper margin, and the hind border of the parietal, 7. 

 It may be, as in Varanus (ib., fig. 2), that an unossified tract of the cranial walls has 

 been left here ; or an angular ridge, as in the Crocodile (ib., fig. 4, 3), may have been 

 broken away. The direction of the occipital surface is more vertical than in Lizards. The 

 mid-tract of the super-occipital is moderately convex transversely, the lateral tracts as 

 moderately concave to the lateral borders of the occiput, which borders gently converge 

 as they rise (PI. II, fig. 1, 3). The exoccipitals (2) extend, connately with the par- 

 occipitals (4), outward, slightly downward and backward, for an extent of 9 lines from the 

 foramen magnum, preserving a vertical breadth of 4 lines. 



In Iguana (PI. II, fig. 3) the super-occipital (3) is a vertical crest, from which the sides 

 slope forward and outward at an acute angle. In Varanus (ib., fig. 2) the super- 

 occipital surface (3) is transversely convex and strongly inclined from the foramen 

 magnum (/) upward and forward. The small Dinosaur, like Dicgnodon, shows a 

 crocodilian type of the occiput. 



The left tympanic (ib., fig. 1, 28) has been dislocated inward, and lies with its upper 

 end beneath the par-occipital abutment (4). 



The pterygopalatine structures accord with the lacertian type. The proportions of 

 the pterapophyses (ib., fig. 5, t) are more like those of Varanus (ib., fig. 6, t) than of 

 Iguana (ib., fig. 7, t) ; but the pterygoid of the small Dinosaur resembles that bone 

 in the herbivorous Lizard. The right pterygoid (fig. 5, 24) retains part of the tympanic 

 process ( a ) and of that ( c ) which abutted against the ectopterygoid (25) ; a portion of the 

 right palatine (20) is preserved, of small size, showing an anterior and posterior emargi- 

 nation, as in Varanus (ib., fig. 6, 20). The hind end of the right maxillary with the abutting 

 part of the ectopterygoid are broken away in the fossil. The right malar bone has left 

 its impression on the matrix (PI. I, fig. 9, 26). 



The masto-postfrontal zygoma (ib., 8 — 12), in its breadth and relative position to 

 the occiput and parietal, is crocodilian. The normal or lower (malo-squamosal) zygoma 

 is indicated on the right side by the impression of the malar and a remnant of the 

 squamosal ; a larger proportion of which is preserved on the left side (PI. II, fig. 1, 27) 

 abutting against the tympanic (ib., 28). It is also shown in PI. I, fig. 9 a, where the 

 parts are drawn without reversing. The upper outlet of the temporal fossa is smaller 

 than in Lacertians, larger than in existing Crocodiles ; its proportions are those of some 

 Teleosaurs and Dicynodonts, and are approached by those of the small Crocodilian from 

 the same Wealden locality (ib., fig. 24, t, t). 



The skull of Scelidosaitrus, which gave the first considerable insight into the type of 

 that part of the Dinosaurian skeleton, had, unfortunately, lost so much of the fore-end as 

 prevented the application of the external narial test of its correspondence with one or 

 other of the two existing divisions of Brongniart's Sauria. It could not, thereby, be 

 determined, for example, whether the outer part or process of the fore-end of the nasal 



