THE WEALDEN AND PURBECK FORMATIONS. vii 



It is interesting to note that the complexities of structure, osteological and 

 dental, manifested by the Iguanodon, and suggesting an analogy to a higher class, 

 should be likewise extended by a manifestation of their presence in an unequivocal 

 Saurian of the same geological epoch, with the same complex type of teeth as 

 in the Iguanodon. The degree of correspondence in this generic character is 

 shown in Plate I of this ' Wealden and Purbeck Reptilia Supplement,' No. 5, 

 where the tooth-crown characteristic of the genus of the small species {Iguanodon 

 Foxii), fig. 10, is shown by the side of a corresponding molar of the larger 

 species {Iguanodon Mantelli, fig. 4). The portion of skull of the small kind 

 (Plate I, fig. 9) supplies acceptably what the larger kind of Iguanodon still lacks. 



In Plate II a lower molar of Iguanodon Foxii is figured, of the natural size (fig. 

 14) and magnified (fig. 15), facilitating the comparison with the mandibular molars 

 of the natural size in the larger species (Plate I, fig. 3). In the same plate the 

 hinder or occipital surface of the smaller species of Iguanodon (Plate II, fig. 1, 

 nat. size) is contrasted with figures of the corresponding part of the skull in the 

 existing Iguana tuberculata (lb., fig. 3). The base of the skull is similarly illus- 

 trated in fig. 5 {Iguanodon Foxii) and fig. 7 {Iguana tuberculata). These parts of 

 Iguanodon Mantelli must be obtained and adequately made known before palsento- 

 logy can be legitimately encumbered with newly invented generic terms. 



The kind and degree of modification of the tooth-crown justifying recognition 

 of a distinct genus of extinct Reptile are manifested in fig. 21, showing the outer 

 surface of an upper molar of Scelidosaurus Harrisonii. In the same plate are 

 given three views, figs. 23, 24, 25, of the instructively preserved skull of Hylceo- 

 champsa vectianus. 



R. 0. 



1st February, 1888. 



