218 



PKOF. H, G. SEELEY ON THE 



[Mar. 21, 



5. On the Primitive Tleptile Procoloplion. 

 By H. G. Seeley, F.R.S., F.Z.S. 



[Received March 21, 1905.] 



(Text-figures 30-38.) 



The Types of Procoloplion. — The two specimens on which 

 Sir R. Owen founded the genus Procoloplion in 1876 are in the 

 British Museum of Natural History. The author was luicertain as 

 to the value of the characters in which P. minor differs from P. tri- 

 goniceps, intimating that it may be a young example of that sj)ecies. 

 The skulls seem to differ in their proportions (text-figs. 30 and 31). 

 P. minor (text-fig. 30) is relatively broader, having the width to 

 length of the skull as 5 to 4. In P. minor the orbits are more 

 distinctly ovate, and placed further forward, being in the middle 



Text-fie-. 30. 



Type specimen of Frocoloplion minor, from Donnj'brook [the sutures are not 

 so distinct in the specimen as in the figure]. 



third of the length of the head, in advance of the parietal foramen 

 and scarcely extending behind the lateral borders of the frontal 

 bones ; the region in advance of the orbits is relatively short ; 

 the quadrate has no expansion backward as in other specimens ; 

 there is no trace of a foramen in the malar arch. Neither fossil 

 gives conclusive evidence of the form of the teeth. Though they 

 are in both types described as conical and pointed, it is not possible 

 to determine the form of the crown when the jaws are closed, as is 



