270 
PROFESSOR H. G. SEELEY ON THE STRUCTURE, ORGANIZATION, 
British Museum, in relieving Dr. Exton’s specimen from the matrix, has shown the 
characters of the fossil in a way which leaves nothing to he desired. 
Procolophon differs widely from Dicynodontia, Gennetotheria, and Theriodontia in 
the structure of the skull, for it possesses no proper temporal fossae. It approximates 
towards the Pareiasauria in features such as the expansion of the parietals roofing in the 
back of the skull and the elongation of the roof bones of the head ; and is remarkable 
for the large size of the epi-otic and quadrato-jugal bones. But, on the other hand, the 
shoulder girdle is dissimilar. There is a laige parietal foramen. Tlie palate is very 
dissimilar in construction to that of a Dicynodont, and, apparently, unlike Pareia- 
saurus in details ; so that the genus becomes the type of a new group, which is, in 
some respects, intermediate between the Pareiasauria and Dicynodontia, and cannot 
be placed in either sub-order. It is the type of the Pi'ocolophonia. 
The skull is sub-triangular, 4'7 centims. long, with the transverse posterior outline 
straight, and measuring 3‘5 centims. from one epi-otic horn to another. Anterior to 
these small posterior angles, the postero-lateral contour is a concave notch, owing to 
the extension outward of the squamosal and quadrato-jugal bone. This post-quadrate 
concavity is about half a circle, and its curve extends forw^ard to a line with the back 
of the orbit, or the middle of the parietal foramen. The great lateral expansion 
anterior to this notch is made by the quadrato-jugal bone ; and these bones widen the 
back of the skull to upwards of 5 centims., for the median measurement to the one 
side on which the preservation is perfect is 2'7 centims. Then the lateral contours 
converge forward, with a moderate constriction towards the front of the orbit, 
terminating in a blunt snout about IT centini. wide below, but the anterior extrem’ty 
containing the nares is lost. 
Superiorly there is a slight bevelling toward the occipital surface, a horizontal 
flattening of the jjarietal and frontal region, a rounding of the nasal and pre-frontal 
area, and an oblique extension outward and downward of the bones below the orbit. 
The circular parietal foramen is 0'4 millim. in diameter, and 9 millims. in advance 
of the back of the skull. The orbits are longitudinally ovate vacuities, 2 centims. 
long; IT centim. wide in front, between the frontal and malar, but narrower behind. 
The least width of the inter-orbital space is rather less than 1 centim. The bones 
which surround the orbit are the malar, post-frontal, parietal, (?) supra-orbital, 
pre-frontal, and lachrymal 
The bones on the two sides of the head are not absolutely identical, partly owing 
to slight differences of form, and partly from differences of preservation. 
Tlie parietal bones are large and irregularly subcjuadrate, with a transverse angular 
bend separating the somewhat narrow, posterior inclined, occipital area from the flat, 
transversely extended, parietal area, which includes the parietal foramen, by narrow 
processes which extend convexly forward between the frontals to ‘enclose it. The 
median suture between the part of the parietals behind the foramen is a zigzag of one 
