520 BRITISH FOSSIL REPTILES. 



Skull and Teeth of Iguanodon Foxii. (' Dinosauria,' Plate 59, figs. 9,9 a, 10; 



Plate 60, figs. 1, 5, 8— IS). 



This unique specimen, for the opportunity of describing which I am indebted to the 

 discoverer, the Rev. W. Pox, M.A., throws much hght upon the cranial characters of 

 the Iguanodon. 



The articular or condylar part of the basi-occipital {Dinosauria, PI. 60, fig. 1, i) is 

 broken away, a portion of the broad basilar part of the bone (ib., fig. 5, i) 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 [f, 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 iq)on 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 [Din., PI. 60, 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 

 extent of 6 lines ; a tract of matrix of 3 lines extent intervenes between the super- 

 occipital, which here shows a jagged upper margin, and the hind border of the parietal, 7. 

 It may be, as in Varanus (ib., fig.. 2), that an unossified tract of the cranial walls has 

 been left here ; or an angular ridge, as in the Crocodile (ib., fig. 4, 3), may have been 

 broken away. The direction of the occipital surface is more vertical than in Lizards. The 

 mid-tract of the super-occipital is moderately convex transversely, the lateral tracts as 

 moderately concave to the lateral borders of the occiput, which borders gently converge 

 as they rise [Din., PI. 60, fig. 1,3), The exoccipitals (2) extend, connately with the par- 

 occipitals (4), outward, slightly downward and backward, for an extent of 9 lines from the 

 foramen magnum, preserving a vertical breadth of 4 lines. 



In Iguana (lb., ib., fig. 3) the super-occipital (3) is a vertical crest, from which the sides 

 slope forward and outward at an acute angle. In Varanus (ib., fig. 2) the super- 

 occipital surface (3) is transversely convex and strongly inclined from the foramen 

 magnum (/) upward and forward. The small Dinosaur, like Dicynodon, shows a 

 crocodilian type of the occiput. 



The left tympanic (ib., fig. 1, 28) has been dislocated inward, and lies with its upper 

 end beneath the par-occipital abutment (4). 



