152 MEMOIRS OF THE CARNEGIE MUSEUM 



may also see, upon this aspect, the conspicuous exoccipital processes. They project 

 almost directly backwards, and only slightly outwards. Posteriorly, the superior 

 occipital area is seen to be bounded above by a sharp and raised line, much curved, 

 which distinctly separates the occipital from the parietal region of the skull. The 

 foramen magnum is very large, and subcircular in outline, its mid-vertical diameter 

 being scarcely shorter than its transverse one. The unnotched condyle is of good 

 size, hemispherical in form, and sessile. 



Seen upon lateral aspect, we are struck with the open, shallow auditory fossa, 

 which is overhung by a raised squamosal ridge, the squamosal process being small. 

 Anterior to this region the lateral wall of the brain case is extensive, smooth and 

 convex, otherwise presenting no special characters. The orbits are large, being con- 

 tinuously circular in front and above, the curve extending from the very short post- 

 frontal process to the lower end of the lacrymal bone. No osseous septum divides 

 these cavities, and a large, median, heart-shaped foramen occupies the central part 

 of the anterior wall of the brain-cavity, from which, during life, the olfactory nerves 

 pass out. Below this another median opening exists, of no inconsiderable size. It 

 is the anterior common aperture of the optic nerves, and it is flanked upon either 

 side by a vertical, scale-like flake of bone, extending forwards. The parial grooves 

 'for the first pair of nerves faintly mark the orbital roof above ; each one leads to 

 a corresponding foramen found over either pars piano, in front. A pars plana or 

 ethmoidal wing is oblong in form, and taken in connection with the lacrymal, makes 

 a very complete osseous partition standing between the eye-socket and rhinal cavity. 

 The mesethmoid is small, and is earned forward for a short distance as a thin median 

 plate of bone, with a free anterior, thin edge. In the forepart of the nasal cavity 

 there are two small foramina, in the otherwise solid wall, which lead forward into 

 the cancellous tissue filling in the upper osseous beak. They are placed side by side. 

 A lacrymal is a peculiarly twisted bone, articulating above with the frontal and 

 nasal. It has an external transverse antero-posterior deep groove above, below which 

 the bone becomes, as it were, twisted and expanded, into a broad quadrilateral plate. 

 This stands transversely and forms, with the corresponding pars plana, the anterior 

 orbital wall. The lacrymal reaches down to the zygoma and is a free bone. In 

 front it has, articulating with its antero-lower angle, a scale-like piece, that stands 

 vertically and rests for its entire length upon the upper surface of the maxillary. 

 This is the supra-maxillary. (Fig. 3 sr.m.) Each zygoma is twisted and much 

 flattened. Anteriorly, their broader surfaces lie in the horizontal plane, while the 

 posterior moieties are in the vertical one. The peg-like, articulatory nibs at their 

 hinder ends for the quadrates are very small. Looking at the skull from a direct 



