§ 13. FOSSIL REPTILES OF SOUTH AFRICA. 553 



Society.* The principal remains hitherto cleared from 

 the rock, belong to reptiles having a narrow cranium, with 

 nostrils divided as in lizards, and not confluent as in turtles, 

 which otherwise the skull in its general appearance much 

 resembles. The orbits are very large; the jaws are eden- 

 tulous, as in the Rhyncosaurus above described : but the 

 upper jaw possesses a pair of long tusks implanted in 

 sockets, like those of the Walrus.^ These tusks are 

 of so fine and dense a texture as to be almost equal in 

 hardness to the canine teeth of the hyena ; the largest 

 specimens are two inches in diameter. The vertebrae, as 

 in most of the extinct saurian s, are sub-biconcave. This 

 marvellous type of reptilian structure is perfectly unique. 



The Acrosaurus, is another extraordinary fossil reptile 

 from the same locality. It has thirty or forty teeth on the 

 alveolar ridge ; and a broad process of the malar bone 

 extending downwards over the side of the lower jaw, as in 

 the Glyptodon (ante, p. 171). 



14. ICHNOLITES, OR FOOTSTEPS ON SANDSTONE. Some 



years since, the attention of geologists was excited by the 

 discovery of supposed impressions of the footsteps of 

 quadrupeds, on the surface of the New Red sandstone, at 

 Corncockle Muir, in Dumfriesshire .{ The imprints resemble 



* But a few of these specimens have been cleared. It is to be 

 regretted that they should be thus neglected, for they probably contain 

 other new and interesting fossil remains. 



t Hence the name Dicynodon, or bidental. See Geol. Trans, vol.vii. 

 p. 53, for a report on the reptilian fossils of South Africa, by Professor 

 Owen. 



X Account of the Marks of Footsteps of Animals found impressed on 

 Sandstone, by the Rev. H. Duncan, D.D. Edinburgh, Trans. Royal Soc. 

 vol. xi. 1828. It is to be regretted that these equivocal markings have 

 received a generic and specific name (Testudo Duncani, Bint. Fos. Rep.) 

 The example has already been followed in America, and the over- 

 burthened nomenclature of Palaeontology is threatened with another 

 century of hard names, applied to mere imprints on stone, the origin 

 of which is still involved in obscurity. 



