FOOTPRINTS OF A DINOSAUR. 119 



supposition that as their huge bodies were borne down on the 

 stream they became disarticulated and dropped by detached piece- 

 meals to the river-bed. 



The skull of /. Bemissartensis is shorter in proportion to that 

 of /. Mantelli, but not as broad. There are some other differences, 

 but not sufficient in Mr. Dollo's opinion, the director of the Koyal 

 Museum of Brussels, to make of it a distinct genus. 



Iguanodon Leedsi, Lyd., from the Oxford Clay, and 7. Prestwichi, 

 Hulke, appear to have some generic differences, from the Wealden 

 Iguanodons, especially in the pendant shape of the middle trochanter 

 and the furrowed shaft of the femur. Both are much smaller than 

 the type, and are now relegated to a new genus, Camptosaurus, 

 Marsh, occurring also in the beds of the United States. It is 

 remarkable that the Sauropterygia culminated in the earlier part of 

 the Mesozoic age, especially the Liassic period. In the Oxford Clay 

 they show a decline in size when Cimoliosaurus took the place of 

 Plesiosaurus, which passed through the Portland and Kimmeridge 

 Clay to the Cretaceous beds. On the other hand the Dinosaurs 

 culminated during the Wealden age and succeeded their smaller 

 representatives of the Kimmeridge and Oxford Clays in new and 

 gigantic forms of the carnivorous Theropoda and herbivorous 

 Sauropoda and Ornitliopoda. 



The seven species of Iguanodon in the Ornithopoda section are 

 /. Hoggii, I. Bemissartensis, I. Mantelli, I. Phillipsii, I. Dawsoni, 

 I. Fittoni, and /. Hollingtoniensis. Of these only one, as already 

 mentioned, has been found in thia formation. Six are from the 

 Wealden and its counterpart, the Wadhurst Clay ; /. Bemissartensis ', 

 I. Mantdli, I. Pliillipsii, L Daicsoni, I. Fittoni, I. Hollingtoniensis a 

 sub-order of Stegosauria. We have Scelidosaurus Harrisoni, Owen, 

 Lias; OmoRctums (Stegosaurus, Marsh) annatus, Owen, 0. Duro- 

 brisensis, Hulke, Kimmeridge Clay ; Hylceosaurus Oweni, Mantel], 

 Polacanthus, Owen, Weald ; Sijngonosaurus, Cambridge Greensand. 

 The last to mention of the herbivorous Dinosaurs are the Sauropoda, 

 characterised by their diminutive brain capacity, which is less 

 relatively than any of the terrestrial vertebrates, and the huge size 



