446 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 18, 



that my largest specimen from the Isle of Wight exhibits traces of 

 the impression of the skin in this region of the foot. 



The metapodial bones of the animal making the tracks here indi- 

 cated must (if the posterior impression was due solely to those 

 bones, and not partly also to the end of the tibia) have been about 

 the size of the largest metatarsal (?) that I have seen from the 

 Wealden beds (Isle of Wight). This was nearly twice the size 

 of the corresponding element of the foot of the half-grown Igua- 

 nodon figured by Owen; and, judging from the vertebrae with 

 which the bone referred to was associated, I am inclined to be- 

 lieve it to have belonged to a Cetiosaurus, or possibly to Poecilo- 

 jpleuron. Further, I possess phalangeal bones, recognized as be- 

 longing to Iguanodon, that indicate an individual large enough 

 to have produced such footprints as those under notice. With 

 regard to the three-toed character of the imprints, it is certain that 

 other Dinosaurians besides the Iguanodon had the same modification 

 of structure* ; and we must not refer these pachydactylous trifids 

 to that animal exclusively. Further, if these rough natural casts 

 of footprints indicate with any exactitude the phalangeal propor- 

 tions of the feet, we might seek to allocate the variously proportioned 

 foot-bones of the different Dinosaurs to the diiferently shaped casts ; 

 but this would be too hazardous a procedure, since the real shape 

 of the foot could have been rarely preserved aright by the clammy 

 mud from which the great brutes dragged their flopping feet. On 

 the firmer ground alone, such as the sandstone on which Mr. Boss 

 has lately found the imprints at Hastings t, could the exact outline 

 of the foot be well preserved. 



Other natural casts of footprints I have found in the Wealden 

 beds of Swanage Bay, at about 200 yards from the western end of 

 the Wealden cliff there. They occur in two bands of sand-rock, 

 usually about 1 foot thick, separated by about 20 feet of clay, and 

 coming down to the sea-shore with the other beds. These casts are 

 of the usual thick-toed trifidal shape, and of the usual size — about 

 15 inches long. 



One specimen of footprint (not a cast), remarkable for its small 

 size (fig. 4), being only about 3 inches long and 3 inches broad, but 

 distinctly trifid like most of the others known, I met with on the 

 shore of the Isle of Wight, about halfway between Brook and 

 Brixton (see section, fig. 1). It was one of several, about 15 inches 

 apart, on a sandstone band, at very low water. 



In the abstracts of my former papers, an ornithic relationship was 

 arrived at as the general conclusion as to my views respecting the 

 uniserial trifid footprints found in the Wealden, and my descrip- 

 tions and remarks certainly gave it foundation ; but in my manu- 

 script, still in the possession of the Society, I also intimated that 

 these bodies were probably connected with the Eeptilian phalanges 

 with which they are associated in the clay and sandstones of the 



* For instance, see the metapodium of Hylceosaurus, figured and described by 

 Prof. Owen, Pal, Soc. Monograph, 1857, p. 18, pi. 11. 

 t See the August Number of the Society's Journal (No. 71, p. 248). 



