PROCOLOPHON PROM THE CAPE COLONY. 801 



out trace of a temporal fossa, and formed by the frontal bones which 

 partly overlap the parietals, is an important difference from the 

 character of that region among lizards, which is always marked by 

 a more or less conspicuous temporal fossa ; but the variable condition 

 of this region in the Chelonia warns us that the expanded forms of 

 the parietal and frontal bones roofing-in the head need not be more 

 than a generic difference in the Lacertilian order. Probably owing 

 to the condition of preservation of the specimen, there are no indica- 

 tions of teeth in the premaxillary bone ; but indications of the pos- 

 terior seven teeth are preserved : they are large, long, cylindrical, 

 tapering to a conical point, which is slightly recurved; each has a 

 large pulp-cavity, prolonged into a short canal, which appears to 

 pierce the crown of the tooth. The teeth are ankylosed to the jaw 

 without trace of fangs or sockets. A fracture through the middle 

 of the specimen shows the palate in the region beneath the orbits to 

 be closed in the median line. The middle region is occupied by 

 rows of teeth, short and conical, which converge forward in a V- 

 shape. Seven teeth in a row on one side in the inner and hinder 

 series on this part of the palate are visible in the space exposed. 

 External and anterior to these teeth there are indications of another 

 parallel series, of which three crowns can be detected. These teeth 

 must be placed on the pterygoid bones. On each side of the teeth 

 the palate is broadly channelled, and the transverse process of the 

 pterygoid which forms the channel is broad and prolonged outward 

 and downward, being homologous with the outer and downward 

 processes of the pterygoid bones of the crocodile. Coupled with the 

 fact that the pterygoid in the specimen previously described must 

 have reached the quadrate bone, this condition of the palate is 

 essentially Lacertian. Below the palate is a mass of bone, which seems 

 too thick to be the central element of the hyoid ; but at the posterior 

 end of the skull, in a corresponding position, are two slender, parallel, 

 cylindrical bones, which would lend support to such a view. 



Procolophon laticeps, Seeley. (PI. XXXII. figs. 4-6.) 



The third skull of Procolophon is larger and relatively much 

 broader. All the hinder part is invested in matrix. It is fractured 

 obliquely behind the foramen parietale, so as to give some indication 

 of the transverse outline of the brain-cavity and of the position of 

 the pterygoid bones. The skull extends markedly beyond the lower 

 jaw both anteriorly and laterally, and the teeth in the maxillary 

 bone are directed inward just as those in the lower jaw are directed 

 upward and outward to meet them. There would seem to have 

 been a very slight displacement of the rami at the symphysis ; but this 

 is probably more the result of crystallization going on in the matrix 

 than of pressure, since the specimen shows no evidence of deformation. 

 This species, in common with the others, has a flattened upper sur- 

 face, cranial bones in pairs, a rounded snout terminated by a pair 

 of narrow premaxillaries, nares similarly placed and looking down- 

 ward laterally, large oblique orbits, similar inflation of the lachry- 

 mal or preorbital region, and subcylindrical teeth ending in conical 



Q. J. G. S. No. 136. 3 h 



