28 Batrachia of the Permian Period of North America, | January, 
limbs were derived; a pelvis; and a cranium nearer that of the 
batrachians than most other fishes present. The Crossopterygia 
are a little on one side of the parental stem, since they have no a 
pelvis, and their limbs begin to show a beginning of that reduc- 
tion and specialization, which is carried to such an extent inthe 
Actinopteri, or typical fishes. : E o; 
view, nevertheless no progress has yet been made by palæonto- 
logical research in filling up the great interval which separates 
the Permian Batrachia from the Mesozoic Mammalia. It is also — 
true that the limb bones of the Permian Reptilian order of the — 
Theromorpha more nearly resemble those of the lowest Mamma- 
lia, the Monotremita, than do those of any other known forms. 
Tae Racaitom. 
I proposed this name! for a division of the Batrachia which j 
predominated during the Permian period in both the old and new a 
worlds. As stated above in the differential table, it is characterized 
by the primitive condition of its vertebral column. The cartilaginous 
chorda dorsalis was present in life, and the vertebral bodies arè 
represented by ossifications of its sheath. In the Trimerorhachide 
this ossification is superficial or cortical, while in the. Eryopide 
it penetrated more deeply into the chorda. The segments of the 
centrum are three in number, an inferior one or intercentrum, and 
a superior lateral one on each side, the pleurocentrum, as it 1 
called by Gaudry. The lateral pieces support the neural arch, | 
and on this account I have called them the centrum proper, 4 
distinguished from the intercentrum. The neural arch is UNS 
broken, and displays articular processes (zygapophyses) of usual 
form, and in some genera a large neural spine. 
The shoulder-girdle of these animals is remarkable for th 
small size of the coracoid element, resembling in this respect the 
salamanders, and approaching the mammals. There is probably 
a clavicle, as has been observed by Gaudry in Actinodon. He 
also finds the three thoracic shields of the Stegocephali (episterna 
and entosternum). I have such bones associated with the Ame 
can forms, but have not yet determined their species. The 
humerus has no head, but a band-like articular surface instea 
1 AMERICAN NATURALIST, 1882, p. 333- 
