FOOTPRINTS OF A DINOSAUR. 117 



the impressions, which could not have been the case if the ground 

 was sandy and not coherent ; otherwise they would be speedily 

 obliterated by the calcareous atoms diffused in the superincumbent 

 water ; and if made on subaerial soil they could not have escaped 

 defacement. 



There are two beds of Wealden Sandstone in Swanage Bay, 

 separated from each other by about 20 feet of clay, in which 

 several tridactyle footprints have been found. 



These two blocks which bear the foot-tracks come from the 

 Corlula beds, higher up in the series than the Feather bed, in 

 which the jaw of the iguanodon was found, described and figured 

 by Sir Kichard Owen in the Palaxmtological Society's publi- 

 cations. The casts of the impressions are well shown on the 

 blocks. The middle toe measures seven inches in length and 

 five inches in breadth, diminishing upwards to a broad obtuse 

 point. The exterior toe is six inches in length and four inches in 

 breadth j the interior toe is five inches in length and three and 

 a-half inches in breadth. Both, like the exterior toe, diminish 

 upwards to a broad obtuse point. The junction of the exterior 

 with the middle toe is lower down in the foot than that of the 

 interior toe. 



Although the Purbeck Beds have yielded many reptilian remains, 

 notably the Swanage Crocodile, Gonioplwlis (three species), NutJietes, 

 Saurillus, and the dwarf crocodiles, Nannosuchus, Tlieriosuclius, the 

 evidence of Dinosaurs is confined to the lower jaw of an Iguanodon 

 from the Feather bed of the Middle Purbecks, and a few records of 

 foot-prints. 



In 1822 Dr. Mantell was the first to find some isolated teeth 

 in the Wealden of the Tilgate Forest, .which he named iguamdon 

 from the resemblance to the iguana now living. In 1834 a large 

 slab of sandstone, now in the British Museum, was found in a quarry 

 near Maidstone, on which were several dorsal and caudal vertebra, 

 portions of the fore and hind-limbs, the clavicle, and the impres- 

 sion of a tooth. In the year 1857 Mr. Beckles exhibited at one 

 of the meetings of the Geological Society the foot of an iguanodon 



