378 me. k. w. hooley ox thb [June 1 913, 



The Frontal. 



In the Atherfield specimen Xo. 1, only the extreme anterior 

 end of the frontal is seen. It commences over the anterior third 

 ■of the orbits, and here on the right side is a curious mammillated 

 knoh of bone (PI. XXXVII, figs. 2 & 5, b.) over the upper border 

 of the orbital rim, which most probably was paired on the left. 

 Interiorly to this boss, the surface is concave, rising into a feeble 

 convexity on the summit of the cranium. The frontal unites 

 with the lachrymals, prefrontals, and the premaxillar prolongation 

 with a V-shaped suture, the angle being towards the oeciput. 

 It lies below the prefrontals and the premaxillar extension, but not 

 beneath the lachrymals along the line of suture. In the hinder 

 portion of the skull in the B.M. E/176 specimen, the extent of 

 the frontal and the other bones of the cranial roof cannot be seen. 

 The cranial platform is a quadrilateral space. 



The Post-Frontal. 



The post- frontal is situated in the corner between the orbit 

 and the supra-temporal fossa. It sends down a process which, 

 in conjunction with the post-orbital (if that bone be present), 

 comprises the posterior boundary of the orbit. 



The Parietal. 



The parietal arches the skull between the supra-temporal fossae. 

 It is extremely constricted, so that it becomes very concave on its 

 lateral borders. At its junction with the occipital area the bone is 

 raised. 



The Squamosal. 



The squamosal is situated at the posterior lower angle of the 

 supra-temporal fossa. It sends forward and upwards a process to 

 unite with the post-fronto-orbital bar, in forming the supra- 

 temporal arcade. Below, it is fused to, and rests upon, the hinder 

 end of the quadrate : this forms a strong buttress, upon which the 

 brain-case is supported. 



The Bones of the Occiput. 



The right side of the back of the skull in B.M. R/176 is 

 destroyed, and the left below the foramen magnum is covered by 

 matrix. Nor are any sutures or striae visible on the upper half, so 

 that the extent of the bones is indecipherable. Except a vertical 

 ridge from the parietal border to the foramen magnum, the 

 whole region between the outer borders is concave. The parietal, 

 squamosals, and paroccipitals have expanded and coalesced into 

 one concave plate, with the post-temporal fossae almost obliterated. 

 The occipital condyle is large, and, as usual, set at right angles 

 to the skull. 



