286 
PROFESSOR H. O. SEELEY OK THE STRUCTURE, ORGANIZATIOK, 
is 5g centims. It is over 2 centims. wide, of a ribbon-like thickness, and curves 
convexly outward, like the squamosal bone, with which its anterior margin may be in 
contact. Its position is suggestive of part of the hyoid. 
The cervical vertebrae of this specimen are described under the vertebral column. 
On a New Skull of Dicynodon tigriceps (Owen) showing the Sutures of the 
Pregmrietal Surface. (Plate 13.) 
In the larger skulls of Anomodouts, it is rare to find the sutures between the 
bones distinctly shown, and I therefore give some notice of a specimen in the Bain 
Collection, hitherto undetermined, which I regard as the anterior part of the skull of 
Dicynodon tigriceps. It is slightly distorted, and shows some difi'erences of character 
in the greater depth of the maxillary bone, in the more anterior direction of the 
great tusk, and, apparently, in the greater prolongation forward of the pre-maxillary 
bones to form the cutting edge of the jaw. These characters are such as might be 
expected to characterize a species, but they are, I conceive, such as might vary with 
age ; and Mr. Boulenger has shown me such extraordinary examples of augmen¬ 
tation of size and variation of proportion in the skulls of some young and adult Frogs 
that, in view of the close correspondence of form and size in the bones of the pre- 
parietal region of the upper surface of the liead, I do not feel justified, with only a 
distorted fragment to work upon, in separating the specimen from tfie type to which 
it is obviously closely allied. 
The specimen shows the relations of the maxillary, pre-maxillary, sub-narial, nasal, 
pi^e-frontal, lachrymal, frontal, and post-frontal bones ; while the nares are exceptionally 
well seen (fig, 2). 
The length of the fragment is only about 30 centims. The pre-maxillary bone is 
shown by a transverse polished section to be single. It is inclined obliquely forward 
and downward, and is constricted posteriorly where it forms the anterior and superior 
borders of the nares. Here its transverse width is 8'5 centims., almost exactly the 
same as in the type skull of D. tigricep>s. It extends backward in a rectangular 
wedge, and penetrates in the median line for some distance between the nasal bones. 
The length of the straight suture by which it joins each nasal bone is 6 centims. 
The length of the bone in the median line to the transverse polished section is 
11 centims., and may have been several centimetres more: these measurements 
correspond with D. tigriceps. In front of the nares the lateral parts of the bone 
bend somewhat abruptly downward and outward for 4*5 centims. to the straight suture 
with the maxillary bone, which is parallel to the superior contour when seen from the 
side, and about 8 centims. long: its direction is also parallel to the median line of the 
skull when seen from above. The ]30sterior lateral border of the bone is concavely 
notched out superiorly to form the front border of the narine, and inferiorly it slopes 
to form the floor on which the sub-narial bone rests. 
