450 ON" IGUANODON PEESTWICHII PROM THE KIMMEKIDGE CLAY. 



4. The same, its upper surface. /, the fibular portion ; t^ the tibial 



portion. 



5. The astragalus {a) and os calcis (c), seen from below. 



6. Front view of the bones of the legs, with the proximal tarsal series : t, 



tibia ; /, fibula ; a, astragalus ; c, calcis. 



7. Side view of same. 



This and the preceding figure are restorations. 



8. The leg and proximal »tar sal elements of a young fowl. The letters indi- 



cate the same parts as in fig. 6. 



9. The hind limb of a chick, showing at this stage the fibula as long as the 



tibia, and the distinctness of the tarsal elements. After Gregenbaur. 



Discussion-. 



Prof. OwEisr stated that a specimen existed in the British Museiiiii 

 ■showing the bones of the hinder limb of a Dinosaur, i. e. Scelido- 

 saurus, which, though, never referred to, gave much information as 

 to the homologies of the bones. This paper, however, was most 

 valuable, and he believed the author had established the specific 

 distinctness of the form. He asked Prof. Seeley what genus in the 

 Mammalia gave a dentition like that of the Triassic Placodus. He 

 found it in Ornitliorhynchus ; but the broad, flat crushers were un- 

 calcified in that sauroid Mammal. 



Prof. Seeley spoke of the high value of Mr. Hulke's paper. 

 Specimens existed in Belgium showing the bones of Iguanodon in 

 situ, and gave independent evidence of the accuracy of the author's 

 conclusions ; but those who had seen them could not, as they had 

 been shown in confidence, describe them. He thought the specimen 

 on the table showed traces of Teleosaurian characters in the ex- 

 panded frontal bone and in other parts of the skeleton. He would 

 even attach more value than the author had done to the dififerences 

 of the vertebral column, pelvis, teeth, and limb-bones from those of 

 the ordinary Iguanodon ; and he thought they might be generic, rather 

 than dependent on age. He attached great importance also to the 

 separation of the astragalus and the os calcis. Here there could be 

 no doubt of specific distinctness from Wealden forms; and he 

 believed that the differences w^ere important enough to justify the 

 author in placing the animal in a new genus. 



Mr. Hulze said he had studied the specimens of Scelidosaurifs 

 much, and doubted whether the bones were truly not displaced. 

 The Belgian specimens, however, gave the fullest evidence of the 

 structure of the Dinosaurian tarsus. 



