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Trmisactions of the Boyal Society of South Africa. 
the best known are Er^ops, Trimerorachis, and Cricotus ; in South Africa 
Stegocephahans are rare in the Lower Karroo, but the only known form, 
Bhmesuchiis, is probably allied to Eryops, and was originally referred to 
that genus by Lydekker. 
While the Lower Karroo fauna cannot have directly sprung from the 
fauna of the American Permian nor the American forms from Karroo 
ancestors, it is manifest that the two faunas are related in such a way as 
to render it practically certain that they are two different modifications of 
the same earlier fauna. The American types are nearer the ancestral, 
though considerably specialised; the African, probably owing to their 
living in the swamps of the Karroo, have developed greater length of 
limb and tended to become more active. The home of the common 
ancestral forms was probably in a southern continent which joined Brazil 
and South Africa. As reptilian remains are extremely rare in beds older 
than those which contain Pareiasaurus and the Therocephalians, though 
the extensive Ecca beds are of exactly the same sort of shale as is found 
in the fossiliferous beds above, we are probably justified in concluding 
that in Lower Permian times reptiles for some reason were very rare in 
South Africa, and as the ancestral Permian fauna must have been 
flourishing elsewhere, we may conclude that it probably was mainly 
confined to the western part of the southern continent. Further, during 
the greater part of Dwyka times there could have been no land verte- 
brates in South Africa, as the land was covered with snow and ice, and 
similar conditions existed in Southern Brazil. Hence the probability 
seems to be that in Upper Carboniferous times the ancestors of the 
Permian reptiles flourished in the northern part of what is now South 
America, and that before the onset of the Permian age representatives of 
most of the types invaded North America, where they soon became 
isolated, and after undergoing considerable specialisation became extinct 
about the middle of the Permian period. The main body of reptiles 
probably passed south as the climate became more temperate. A few 
forms probably extended across the continent shortly after the glacial 
conditions disappeared, as, for example, Mcsosaurus, and others of a more 
hardy sort gradually followed. But it was apparently not till near the 
middle of Permian times that the large body of the Permian types arrived 
in South Africa. 
In South Africa the conditions must have been such as to promote 
rapid evolution, and many new types soon appeared. The most remark- 
able are the Anomodonts, which are evidently greatly specialised descen- 
dants of some Therocephalian-like type, but Dicynodon is not likely to 
have sprung from any known Therocephalian and may have evolved from 
a somewhat more primitive type more nearly allied to the Dinocephalians. 
From the great variety of Anomodonts found in South Africa and from 
