OF HYPSILOPHODON POXII. 
1037 
and of the end of the snout, making its total length 10*6 centims. The width at the 
occipito-parietal crest is 22 millims.; at the middle of the parietal region it decreases 
several millims.; at the fronto-parietal suture it increases to 33 millims.; between the 
orbits it slightly contracts ; in front of these cavities it again slightly expands; and 
thence lessens to the end of the snout. 
This is evidently the skull of an immature individual. A skull in my own collec¬ 
tion (Plate 71, fig. 1) (No. 110 Catal., Coll. Hulke) was probably 5 centims. longer, 
and I have seen fragments which indicate that this greater length was sometimes 
exceeded. 
For convenience, first the occiput, then the upper surface, next the under surface 
of the skull, and lastly the dentition will be described. 
Occiput. —The occipital plane in Mr. Fox’s type skull (Plate 71, fig. 3) includes an 
acute angle with the upper surface, but it is probable that the inclination of these 
surfaces is exaggerated by the crushing to which the skull has been subjected. The 
occipital condyle (oc.), 9 millims. in its horizontal diameter, is more wide than deep. 
The margin of the foramen magnum is slightly swollen. Above the foramen the surface 
is divided by a median ridge. A large par-occipital process, 23 millims. long (popr.), 
stands out from the sides of the occiput in the level of the upper part of the foramen 
magnum. Owing to the damage this part of the skull has undergone, effacing the 
sutures, the respective shares of the several bones composing the occiput cannot be 
now fixed with precision, but it may, I think, be safely stated that the supraoccipital 
enters largely into the foramen magnum, as in Iguanodon Prestwichii * 
Upper surface of skull .—The parietal bone ( pa .) appears to me single, as in 
Iguanodon Mantellii and I. Prestwichii. I find no unequivocal evidence of an inter¬ 
parietal suture. Its two halves meet in an angular crest, which behind is prolonged 
beyond a fine drawn transversely to the long axis of the skull through the meeting of 
the upper and the posterior surfaces, and overhangs the supraoccipital bone. 
From this median supraoccipital process the posterior border of the parietal bends 
outwards, joining the inner branch of the squamosal, with which it bounds posteriorly 
the upper opening of the temporal fossa (Plate 71, fig. 2). Anteriorly the parietal 
crest declines, and ends at the interfrontal suture. From a point slightly in advance 
of the middle of the crest a slight ridge-like elevation of the surface curves outwards 
to the post-frontal bone. It marks an expansion of the front half of the parietal bone, 
as occurs in Iguanodon Mantelli\ and I. Prestwichii .§ 
The frontal bones (fr.) are remarkably large (Plate 71, figs. 1, 2). The suture joining 
their median borders is slightly raised. Their orbital border also is prominent, which 
makes the upper surface between the orbits slightly concave in a direction transverse 
* Hulke, J. W., Quart. Journ. Geol. Soc., vol. 36, plate xviii., fig. 3. 
t Ibid., vol. 27, plate xi., fig. 3. 
X Ibid., vol. 36, plate xviii., figs. 1, 2. 
§ Ibid., vol. 27, plate xi., fig. 3. 
