SKULL OF A PARIASAURIAN REPTILE, 169 
found in Pariasaurus, and in a more primitive form in Ptero- 
plax and other Embolomerous Stegocephalia. 
It may at some future time be possible to bring this bone 
into relation with the so-called alisphenoids of Crocodiles, which, 
as is already generally recognized, have nothing to do with the 
mammalian alisphenoid, but in the present state of our knowledge 
of the development of the crocodile skull it is unwise to institute 
such a comparison. 
With regard to the identification of the nerve-exits little can 
be said. The large foramen is undoubtedly for the optic nerve, 
and the small foramen above it can only be for the trochlearius, 
its peculiar position being somewhat paralleled by a metamor- 
phosing skull of Kana temporaria figured by Gaupp, fig. 372, 
Band iii. Hefte 2, of Hertwig’s ‘ Handbuch der Entwicklungs- 
lehre.’ 
Palate-—The palate of Pariasaurus only differs from the 
primitive reptilian condition in the fact that the pterygoids 
extend forwards over the prevomers to reach the premaxille. 
I believe this;unusual character to be an adaptive one. The 
whole palate of Pariasaurus is covered with a unique armature 
of small, sharply pointed teeth. The whole structure is such 
as to give very great strength to the roof of the mouth. The 
bone is thick, the middle line is raised into a ridge which forms 
a girder along the dorsal surface; in the prevomerine region 
this may be six centimetres deep; posteriorly the pterygoids are 
supported by the anterior end of the parasphenoid which, with 
the massive sphenethmoid above it, form a rigid connection 
between the palate and the roof of the skull. Finally, the palatine 
is supported about the middle of its area by the descending 
process of the prefrontal. The whole forms an assemblage of 
supports scarcely paralleled in any other type. 
Squamosal.—The presence of only one bone in the temporal 
region makes it necessary to discuss which of the three bones of 
a primitive reptile has survived in Pariasaurus. 
The relations of the quadrate in all Embolomerous, Rachi- 
tomous, and Stereospondylous Stegocephalia are in essentials 
identical, although they have seldom been accurately described, 
probably because they are usually best shown in broken and 
unpromising looking fragments. In all types of which I have 
been able to examine satisfactory material [Pteroplux, “ Lox- 
omma,” ‘* Bothriceps,” Micropholis, Capitosaurus, Trematosaurus, 
Batrachosuchus, Aphaneramma, and others] the quadrate is a bone 
consisting essentially of a thick lower margin, provided with 
condyles for the articulation of the lower jaw, from which runs 
a thin plate which inclines more or less forwards. The posterior 
surface of this plate is covered to a greater or less degree by the 
posterior ramus of the pterygoid, which in later types is con- 
nected with a thin vertical wall rising nearly to the roof of the 
skull, and by the posterior edge of the outer and lower of the 
