2l8 HISTORICAL PALEONTOLOGY. 



now certain that the Elgin sandstones which contain Telerpeton 

 Elginense, as this reptile is termed, are really to be regarded as 

 of Triassic age. By Professor Huxley, Telerpeton is regarded 

 as a Lizard, which cannot be considered as " in any sense 

 a less perfectly - organised creature than the Gecko, whose 

 swift and noiseless run over walls and ceilings surprises the 

 traveller in climates warmer than our own." The "Elgin Sand- 

 stones" have also yielded another Lizard, which was originally 

 described by Professor Huxley under the name of Hyperoda- 

 pcdon, the remains of the same genus having been subsequently 

 discovered in Triassic strata in India and South Africa. Tne 

 Lizards of this group must therefore have at one time enjoyed 

 a very wide distribution over the globe ; and the living Spheno- 

 don of New Zealand is believed by Professor Huxley to be the 

 nearest living ally of this family. The Hyperodapedon of the 

 Elgin Sandstones was about six feet in length, with limbs 

 adapted for terrestrial progression, but with the bodies of the 

 vertebrte slightly biconcave, and having two rows of palatal 

 teeth, which become worn down to the bone in old age. 

 Lastly, the curious Rhynchosaurus of the Trias is also referred, 

 by the eminent comparative anatomist above mentioned, to the 

 order of the Lizards. In this singular reptile (fig. 151) the skull 



is somewhat bird-like, and the 

 jaws appear to have been desti- 

 tute of teeth, and to have been 

 encased in a horny sheath like 

 the beak of a Turtle or a Bird. 

 It is possible, however, that the 

 palate was furnished with teeth. 

 The group of the Crocodiles 

 and Alligators (Crocodilia], dis- 

 tinguished by the fact that the teeth are implanted in dis- 

 tinct sockets and the skin more or less extensively provided 

 with bony plates, is represented in the Triassic rocks by the 

 Stagonolepis of the Elgin Sandstones. The so-called "Theco- 

 dont" reptiles (such as Belodon, Thecodontosaums, and Palao- 

 saurus, fig. 152, c, d, e) are also nearly related to the Croco- 

 diles, though it is doubtful if they should be absolutely referred 

 to this group. In these reptiles, the teeth are implanted in 

 distinct sockets in the jaws, their crowns being more or less 

 compressed and pointed, " with trenchant and finely serrate 

 margins " (Owen). The bodies of the vertebrae are hollowed 

 out at both ends, but the limbs appear to be adapted for pro- 

 gression on the land. The genus Belodon (fig. 152, c] is 

 known to occur in the Keuper of Germany and in America ; 



