FAUNAL RELATIONS OF EARLY VERTEBRATES 393 
what evidence he could for the Permian age of this fauna and has 
admittedly failed in proving anything save its utter isolation, and 
from the evidence we yet have no one can do better than he has done. 
The fauna was literally suz generis and I may almost say sui ordints. 
But two or three genera of two types out of the scores of genera known 
from these regions can be correlated as showing resemblances— 
family resemblances I mean—with foreign forms. And both of these 
types had made their appearance, admittedly now here in America, 
before the close of the Pennsylvanian, one the derivative of Upper 
Carboniferous, possibly sub-Carboniferous stock, the other a later 
development, and both continuing for a brief period in Europe during 
Permian times. Of all the remainder of the air-breathers not one 
can be compared with forms known elsewhere in the world, save in 
the general characters, ordinal characters at best. 
These facts can mean but one thing, the faunal isolation of land 
and freshwater vertebrates during all of the so-called Permian times 
in America. The faunistic evolution here was great, however. At 
least three very distinct phyla of reptiles and as many of amphibia are 
known with certainty: the Pelycosaurs (Naosaurus, Dimetrodon, 
etc.), derivatives of a prior type which had branched off before the 
close of the Pennsylvanian; the true Cotylosaurs (Otocoelus, Diadectes, 
etc.) with, in some cases, singular developments of dermal carapace, 
strongly suggestive of the turtles, unknown elsewhere; and a third 
type (Labidosaurus, Pariotichus, etc.), for the present nameless, 
small crawling reptiles with large head, short tail, short limbs, whose 
nearest, but remote relatives are found among the pareiasaurs of 
South Africa, doubtless derived from the same common stock as the 
pareiasaurs, but modified by long isolation. Of the amphibia the 
most numerous and best developed are those with temnospondylous 
vertebrae, that is those which have the vertebrae divided into separate 
elements, the type from which the mammals doubtless eventually 
arose, as well as the cotylosaurs, and pareiasaurs. This group is also 
abundantly represented in the Lower Permian of Europe, but reached 
the highest expression in the Texas Permian (Eryops) A second 
type, represented by a few forms, in America, known from the latter 
part of the Pennsylvanian throughout the Permian (Diplocaulus, 
Crossotelos, etc.) represents sparsely the continuation of the microsaurs 
