WEALDEN DINOSAURS. 521 



The pterygo-palatine 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, i) ; 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 (J 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. 59, 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. 60, fig. 1, 27) 

 abutting against the tympanic (ib., 28). It is also shown in PI. 59, 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 Scelidosaurus, 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 

 applied itself to the anterior edge of the ascending process of the maxillary, or to that of 

 the premaxillary ; in other words, whether the maxillary entered into the formation of 

 the outer nostril, as in Lacertilia, or was excluded therefrom, as in CrocodUia. 



The present Dinosaurian skull supplies this test and shows its correspondence with 

 the Crocodiles ; there is, nevertheless, a touch of the Lizard. For the body or jaw-part of 

 the premaxillary {Din., PI. 59, fig. 9, 22) sends upward not only the process from its hinder 

 part (22'), applying itself to the outer border of the fore-part of the nasal (15) and 

 excluding therefrom the maxillary (21), but it also sends upward a more slender process 

 from the fore-part, which terminates in a point wedged between the ends of the nasals 

 and dividing the right nostril (« ) from the left, after the lacertian type. Yet, again, the 

 Crocodilian affinity is here manifested, for the premaxillaries are not confluent and 

 the dividing process is not a single and symmetrical one, as in Iguana, Varanus, and 

 most Lizards,^ but is bisected by the medial suture or cleft dividing the right from the 

 left premaxillary. The premaxillary thus, in the main, adheres to the type of that of 

 the Crocodile, circumscribing all that part of the nostril which is not due to the nasal 



^ Hatteria {Rhynchocephalus) is an exception (' Phil. Trans.,' 1862, plate xxv, fig. 5, 22, p. 46"). 



