﻿4 



FOSSIL REPTILIA OF THE 



The close interlocked fitting of these teeth of different stages and periods of growth is 

 most instructively shown in the present specimen ; former ones had given only a partial 

 view of this arrangement, suggestive, however, of an Iguanodontal character of dentition, 

 which is here demonstrated. 



The primary and secondary ridges are more equally developed, and the tertiary ridges 

 less conspicuous, in these lower teeth of a Purbeck Iguanodon than is usual in the larger 

 or older Wealden specimens. If any Palaeontologist should see in this a specific character 

 he may, perhaps, accept the name of Iguanodon Hoggii. 



§ 2. Skull and Teeth of Iguanodon Foxii. Plate I, figs. 9, 9 a, 10; Plate II, 



figs. 1, 5, 8—18. 



This section of the present Monograph may be regarded as a Supplement to the 

 paper by Professor Huxley, F.R.S., F.G.S., in the 26th volume of the £ Quarterly Journal 

 of the Geological Society,' p. 3, PI. I, figs. 1 — 4 (1870), in which its chief subject has 

 been described and figured with characteristic care. The conclusions of the author as 

 to the generic relationship of the species to which this unique fossil skull belonged, were 

 not, however, satisfactory to its discoverer, and he, consequently, placed the specimen in 

 my hands. 



The desirability of throwing light upon the cranial characters of Iguanodon, 

 supposing it should be admitted that there may be here a source of such, will serve, I 

 trust, as an excuse with palaeontologists generally, for my presuming to go over ground 

 already trodden by so able a predecessor, and the result may be that the Rev. W. Fox 

 will not stand alone in rejecting the ascription of his fossil to a genus " Hyjjsilojjhodon." 



The articular or condylar part of the basi-occipital (PI. II, fig. 1, l) is broken away, a 

 portion of the broad basilar part of the bone (ib., fig. 5, l) remains in articulation with the 

 basi-sphenoid (ib., ib., 5). This element shows a median contraction with lateral 

 emarginations, bounded anteriorly by the pair of pterapophyses (t, t). The left of these 

 abuts in its natural position against the corresponding pterygoid, the hinder branch of 

 which, diverging obliquely backward, is broad and moderately concave on its postero- 

 internal surface ; the end which would have abutted upon the inner and back part of 

 the tympanic is broken off. There is no apparent " pre-sphenoid style " from the 

 interspace of the pterapophyses. 



The left half of the foramen magnum (PI. II, fig. 1/) is entire, showing a vertical 

 diameter of 4 lines, a transverse one of 5 lines ; the lower part shows the fractured 

 surface from which the left exoccipital portion of the occipital condyle has been 

 broken away : the basi-occipital part of the condyle is wanting. The super-occipital 

 (ib., ib., 3) rises broadly and vertically from the upper half of the foramen,/, for an 



