A FOSSIL REPTILE. Ae 
3. The loss of the primitive connection between the squa- 
mosal and pterygoid. 
The loss of the ‘‘ supra-” and inter-temporal bones. 
The reduction of the lachrymal so that it no longer 
reaches the nostril. i 
The release of the distal end of the stapes from the 
quadrate. 
7. The short atlas and long axis. 
8. The long neck. 
9 
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9. The extreme reduction of the plastron. 
10. The loss of the cleithrum. 
11. The loss of the supraglenoid and glenoid foramina. 
12. The loss of the screw-shaped glenoid cavity. 
13. The loss of the fifth distal carpal. 
14. The loss of the centralia tarsi and the fifth distal tarsal. 
The specialisations in the structure of Procolophon are :— 
1. The enlarged tabulare. 
The enlarged quadratojugal. 
The enlarged orbit. 
The dentition. 
The characteristic humerus. 
The non-ossification of the radiale. 
The three sacral vertebre. 
MI OU HE Oe bo 
No other Cotylosaurians approach Procolophon in the number 
of its advances, no other form has the lachrymal excluded from 
the nostril, and none other has completely lost the screw-shaped 
glenoid cavity. These differences, however, are not of such a 
character as to preclude the possibility of Procolophon having 
been derived from some known earlier form; they are merely 
a result of its lateness in time. 
The very large otic notch seems by itself to render any con- 
nection with the Captorhinide impossible; but of even greater 
importance is the difference in the brain-cases. Procolophon has 
the vestibule of the inner ear occupying the whole side-wall of 
the cranium, and in wide connection with the brain-cavity, exactly 
as ina Tortoise or Sphenodon. The Captorhinids, although the 
material is not sufficiently good for certainty, seem to have the 
vestibule placed very low down, as in a Therapsid; a difference 
of this character seems to me to render any idea of a close 
connection between the groups quite unbelievable. 
So little is known of Pariotichus and Pantylus that their 
affinities are quite uncertain. | 
Pariasaurus differs from Procolophon in its very long, low 
brain-cavity, with a bony separation of the inner ear from the 
cranial cavity. It is, of course, a very much less advanced type, 
retaining a concave occipital condyle, a trace of the connection 
of the squamosal and pterygoid, a lachrymal reaching the nostril, 
