Royal Society. 131 



In the sandstone of TiJgate Forest, near Cuckfield, in Sussex, 

 which belongs to the iron-sand formation, and forms part of a 

 chain of hills extending from Hastings to Horsham, are found the 

 teeth and a few of the bones of the subject of this paper, together 

 with those of a gigantic species of crocodile, of the megalosaurus 

 and the plesiosaurus, and the remains of turtles, birds, and vege- 

 tables. The author, some time since, sent specimens of the teeth to 

 various naturalists ; in particular to M. le Baron Cuvier, whose 

 opinion of them coincided with his own, that they belonged to an ex- 

 tinct herbivorous reptile hitherto undescribed. With the assistance 

 of Mr. Clift, he had subsequently compared them with those of a 

 skeleton of the recent Iguana of the West Indies, in the museum 

 of the Royal College of Surgeons, with which he found them to 

 possess a close affinity, and he details, in this notice, the particu- 

 lar results of the comparison ; adverting, also, to the probable 

 station of the extinct animal in the order of Saurians. From the 

 affinity just mentioned, and at the suggestion of the Rev. W. D. 

 Conybeare, he had given it the name of Iguanodon. On the 

 supposition that the proportions of the parts in the extinct ani- 

 mal were the same as in the recent, Mr. Mantell infers that the 

 Iguanodon must have exceeded in size even the megalosaurus, and 

 have been upwards of sixty feet in length. From the fossils asso- 

 ciated with its remains, he concludes, tliat if an amphibious, it 

 was not a marine reptile, but inhabited rivers and freshwater 

 lakes. Drawings of the teeth and bones of the Iguanodon were 

 annexed to this communication. 



February 24. — The reading was commenced of a paper On the 

 Maternal- Fcetal Circulation; by David Williams, M.D., com- 

 municated by Dr. Thomas Thomson, F.R.S. 



March 3. — The reading of Dr. Williams's paper was resumed 

 and concluded. This essay gave an account of the different spe- 

 culations entertained on the nature of the medium circulating be- 

 tween the uterine and umbilical vessels, ahd considered the evi- 

 dence brought forward in their support to be unsatisfactory. It 

 then stated, that it had occurred to the author that it might bo 

 practicable to arrive at more satisfactory proofs in favour of one 

 or the other of these speculations, by observing the phaznoinena 

 which would present themselves in the foetal vessels on injecting 



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