KEPTILIA. 
27 
not confined to the edge of the 
jaw, while the ribs are single¬ 
headed. Proterosaurus occurs 
in the Upper Permian of Ger¬ 
many and England, but is only 
imperfectly known. Hyperoda- 
pedon (Fig. 22) is Triassic 
both in Britain and in India, 
and is represented in Wall- 
case 9 by a fine skeleton of 
H. gordoni in a slab of sand¬ 
stone from Elgin, also by 
fragments from various other 
localities. Rhynchosaurus, from 
the Trias of Grinshill, Shrop¬ 
shire, is smaller than Hyper- 
odapedon and equally well 
known. There is also a good 
skeleton of the smaller Pleuro- 
saurus from the Upper Jur¬ 
assic Lithographic Stone of 
Bavaria. 
Dimetrodon and Naosaurus, 
from the Permian of Texas, 
U.S.A., seem to be Bhyncho- 
cephalians, and are remarkable 
for the length of their verte¬ 
bral neural spines, which bear 
lateral processes (Fig. 23). 
Fig. 23.—Anterior view of a dorsa 
vertebra of Naosaurus claviger, 
from the Permian of Texas, 
U.S.A.; one-sixth nat. size. ce. 
centrum or body of vertebra. 
(Fragments in Table-case 14.) 
Order VI.— ANOMODONTIA or THEROMORPHA. 
The most characteristic reptiles of the Permian and 
Triassic periods are intermediate in organisation between the 
early Amphibia and the true Reptilia and Mammalia of later 
times. They are sometimes named Anomodontia (“ irregular 
toothed”), in allusion to the varied and unusual character 
of their teeth, while they are sometimes described as Thero- 
morpha (“ beast-shaped ”), from their evident relationship to 
the warm-blooded mammals or “ beasts.” They approach 
mammals (i.) in the reduced size of the quadrate bone and of 
the adjoining bones in the lower jaw, (ii.) in the frequently 
well-formed single bony bar or “ malar arch ” over the biting 
Wall-case 
9. 
Table-case 
14. 
Wall-cases 
9, 10. 
Table-cases 
30-33. 
