218 HISTORICAL PALZONTOLOGY. 
now certain that the Elgin sandstones which contain Zelerpeton 
Elginense, as this reptile is termed, are really to be regarded as 
of Triassic age. By Professor Huxley, Ze/erpeton 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 Hyferoda- 
pedon, the remains of the same genus having been subsequently 
discovered in Triassic strata in India and South Africa. The 
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 WyZerodapedon of the 
Elgin Sandstones was about six feet in length, with limbs 
adapted for terrestrial progression, but with the bodies of the 
vertebre slightly biconcave, and having two rows of palatal 
_ teeth, which become worn down to the bone in old age. 
Lastly, the curious AhAynchosaurus 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 lke 
the beak of a Turtle or a Bird. 
It is possible, however, that the 
nn Sins ae ee palate was furnished with teeth. 
eee Teas an Ale Owe) The group of the Crocodiles 
and Alligators (Cvocodilia), 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, Thecodontosaurus, and Paleo- 
saurus, fig. 152, ¢, 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 Be/odon (fig. 152, ¢) is 
known to occur in the Keuper of Germany and in America ; 
