6 FOSSIL REPTILIA OF THE 



It bears the same proportion to the femur as does the tibia in the specimen 

 figured in Tab. II. 



The bone, with the shaft crushed flat, and with a sub-bilobed end (figs. 8 and 9), 

 having the opposite extremity broken away, more resembles a tibula than it does 

 a metatarsal bone. 



The bone (figs. 10 and 11) presents the characters of a metatarsal at both its 

 articular extremities, and might well belong, by its general proportions, to the 

 same limb with the femur (fig. 5) and tibia (fig. 7) of Tab. III. Fig. 12 gives a 

 side view, fig. 13 a back view, and fig. 14 a front view, of a proximal phalanx of 

 one of the toes of a foot of corresponding dimensions. 



A tarsal bone (Tab. Ill, fig. 15) presents a peculiar form; one of the larger 

 surfaces («) is impressed with a shallow cavity ; it is separated from the opposite 

 surface, for two thirds of its extent, by a smooth, convex, apparently articular, 

 surface, broader at one end of the bone than at the other. The other third of the 

 marginal surface (b) presents a triangular, rather flattened, facet. The opposite 

 surface to a is also impressed by a cavity, bounded by a sharper margin, which at 

 one end is notched, so that two slight angular projections here appear, as at 

 h, fig. 15. 



The vertebral centrum presents one terminal surface flat, the other slightly 

 convex ; it belongs to the dorsal or lumbar series, all the processes having been 

 developed from the neural arch, which has separated from the sutural surfaces 

 shown in fig. 2. The sides of the centrum (fig. 1) are smooth, concave length- 

 wise, convex vertically, converging towards the lower border, but in a less degree 

 than in Iguanodon ; that border is consequently less narrow. The neural canal 

 sinks at the middle into the substance of the centrum (fig. 2). All the characters 

 of this part agree with the Dinosaurian nature of the young reptile which is 

 demonstrated by the femur (figs. 5 and 6). 



From the texture, fragility, and evidences of incomplete ossification of the 

 bones represented in Tab. Ill, I infer them to have belonged to a very young 

 individual, and their occurrence in a marine deposit suggests many reflections. 



To whatever extent the Saurian organization has been modified for terrestrial 

 life, that has been, in no instance, such as to suggest an inability to swim. On 

 the contrary, the disproportionate shortness of the fore limbs, even in the Igua- 

 nodon, leads to the suspicion that they might be short in reference to diminishing 

 the obstacles to propelling the body through water by actions of the strong and 

 vertically extended tail ; and that, as in the living land lizard of the Gallopagos 

 Islands, called Amblyrhynchas, the fore limbs might be applied close to the trunk in 

 the Iguanodon, when it occasionally sought the water of the neighbouring estuary 

 or sea. One would suppose that the newly born or newly hatched young of a 

 Dinosaur might be safer on shore than at sea, or at least in waters which, like 



