304 Analym of Scientific Books. 



curate bisection of the star, or imperfections in the micrometer 

 screw. 



viii. Notice on the Iguanodon^ a newly'discovered Fossil Reptile, 

 from the Sandstone of Tilgate Forest^ in Sussex. By Gideon 

 Mantell, F.L.S. and M.G.S'.^Felloiv of the College of Surgeons, <^c. 

 In a Letter to Davies Gilbert, Esq., M.P., V.P.R.S., ^^c. 8^c. 8^c. 

 Communicated by D. Gilbert, Esq. 



The sandstone of Tilgate Forest is a portion of that extensive 

 series of arenaceous strata, which constitutes the iron sand 

 formation, and in Sussex forms a chain of hills that stretches 

 through the county in a W.N.W. direction, extending from 

 Hastings to Horsham. In various parts of its course, but more 

 particularly in the country around Tilgate and St. Leonard's Fo- 

 rests, the sandstone contains the remains of saurian animals, 

 turtles, birds, fishes, shells, and vegetables. Of the former, 

 three, if not four, species belonging to as many genera are 

 known to occur, viz., the crocodile, megalosaurus, plesiosaurus, 

 and the iguanodon, the animal whose teeth form the subject of 

 this communication. The existence of a gigantic species of cro- 

 codile in the waters which deposited the sandstone, is satisfac- 

 torily proved by the occurrence of numerous conical striated 

 teeth, and of bones possessing tJie osteological characters peculiar 

 to the animals of that genus ; of the megalosaurus, by the pre- 

 sence of teeth and bones resembling those discovered by Professor 

 Buckland in the Stonesfield slate ; and of the plesiosaurus, by 

 the vertebrae and teeth analogous to those of that animal. 



The teeth of the crocodile, megalosaurus, and plesiosaurus, 

 differ so materially from each other, and from those of the other 

 lacertae, as to be identified without difficulty ; but in the summer 

 of 1822, others were discovered in the same strata, which, al- 

 though evidently referrible to some herbivorous reptile, possessed 

 peculiar characters. Mr. Mantell, therefore, endeavoured to dis- 

 cover such connected portions of the skeleton as might determine 

 the nature of their former owners, but in vain ; but on com- 

 paring them with the teeth of certain recent lacertae, he disco- 

 vered their correspondence with those of a species of iguana, 

 which are delineated in annexed plate. 



Whether the animal to which the fossil teetli belonged should 

 be considered as referable to existing genera, differing in its spe- 

 cific characters only, cannot at present be determined. " But," 

 says Mr. M,, " if any inference may be drawn from the nature of 

 the fossils with which its remains are associated, we may con- 

 clude, that if amphibious, it was not of marine origin, but inha- 

 bited ri\'ers or fresh- water lakes ; in either case the term 

 iguanodon, derived from the form of the teeth, (and which I 



