OWEN.—CLASSIFICATION OF REPTILIA. 83 
bones and bone fragments. The largest known species are the P. Sedqwickii and 
P. Fittoni, from the upper greensand of Cambridgeshire. Finally, the Pterodae- 
tyles of the middle chalk of Kent, almost as remarkable for their great size consti- 
tute the last forins of flying reptile known in the history of the crust of this earth, 
Order VII. Thecodontia.——V ertebral bodies biconcave: ribs of the trunk long 
and bent, the anterior ones with a bifurcate head : sacrum of three vertebree: limbs 
ambulatory, femur with a third trochanter. Teeth with the crown more or less 
compressed, pointed, with trenchant and finely serrate margins: implanted in diss 
tinct sockets. This order is represented by the extinct genera Thecodontosaurus 
and Paleosaurus of Riley and Stutechbury, from probably triassic strata, near 
Bristol: by the Cladyodon of the New Red Sandstone of Warwickshire, with 
which, probably, the Belodon of the Keuper Sandstone of Wirtemberg is generi- 
eally synonymous. The Bathygnathus, Leidy, from New Red Sandstone of Prince 
Edward’s Island, North America, is probably, a member of the present order; 
which seems to have been the forerunner of the next. 
Order VIII. Dinosawria.—-Cervical and anterior dorsal vertebree, with par- and 
di-apophyses, articulating with bifureate ribs: dorsal vertebr with a neural plat- 
form ; sacral vertebre from four to six in number. Articular ends of the free ver- 
tebree, more or less flat; but in the cervical becoming convex in front and concave 
behind, in some species. Limbsambulatory, strong, long and unguiculate, Femur 
with a third trochanter insome, The species of this order were of large bulk, 
and were eminently adapted for terrestrial life; some, e. g., Iguanodon and, proba- 
bly, Hyleosaurus, were more or less vegetable feeders; others, e. g., Megalosar, 
were carnivorous. The Dinosauria ranged, in time, from the lias (Scelidosaurus 
Ow., from Charmouth) to the upper greensand (Iguanodon). The Megalosaurus 
occurs in the lower oolite to the Wealden inclusive. The latter formation is that 
in which the Dinosauria appear to have flourished in greatest numbers and of 
hugest dimensions. 
Order 1X. Crocodilia.—Teeth in a single row, implanted in distinct sockets, 
external nostril single and terminal or subterminal. Anterior trunk; vertebra 
with par- and di-apophyses, and bifureate ribs; sacral vertebrze two, each support- 
ing its own neural arch. Skin protected by bony, usually pitted, plates. 
Sub-Order Amphicelia (audr, both ; kordos, hollow; the vertebree being hollow 
ed at both ends).—Crocodiles, closely resembling in general form the long and 
slender-jawed kind of the Ganges, called Gavial, existed from the time of the 
deposition of the lower lias. The teeth of the liassic forms were similarly long 
slender, and sharp, adapted for the prehension of fishes, and their skeleton was 
modified for more efficient progress in water, by both the terminal vertebral sur 
faces being slightly concave, by the hind limbs being relatively larger and 
stronger, and by the orbits forming no prominent obstruction to progress through 
water. From the nature of the deposits containing the remains of the so-modified 
crocodiles they were marine. The fossil crocodile from the Whitby lias, deseribs 
ed and figured in the Philosophical Transactions, 1758, p. 638, is the type of these 
Amphicelian species. They have been grouped under the following generic 
heads:—Teleosaurus, Mystriosaurus, Macrospondylus, Massospondylus, Pelagosau- 
