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vertebre of the frog, indicating an habitual inflexion of the spine, 
analogous to that in the humped back of the frog. The neurapo- 
physes are anchylosed to the vertebral body. ‘The spinous process 
rises from the whole length of the middle line of the neurapophysial 
arch, and its chief peculiarity is the expansion of its elongated sum- 
mit into a horizontally flattened plate, sculptured irrregularly on the 
upper surface. A similar flattening of the summit of the elongated 
spine is exhibited in the large atlas of the toad. The body of the 
vertebr agrees with that of the L. leptognathus. The humerus 
is an inch long, regularly convex at the proximal extremity, and 
expanded at both extremities, but contracted in the middle. A 
portion of a somewhat shorter and flatter bone is bent at a sub- — 
acute angle with the distal extremity, and resembles most nearly 
the anchylosed radius and ulna of the Batrachia. 
The femur wants both the extremities; its shaft is subtrihedral 
and slightly bent, and its walls are thin and compact, including a 
large medullary cavity. The tibie are as long, but thicker and 
stronger than the femur. They had lost their articular extremities, 
but exhibited that remarkable compression of their distal portion 
which characterizes the corresponding bone in the Batrachia: they 
likewise have the longitudinal impression along the middle of the 
flattened surface. The length of the more perfect shaft is 2 inches 
1 lme. The precise nature of the broad flat bone, Mr. Owen had 
not determined. 
With respect to the osseous dermal scute, Mr. Owen remarks, 
that though they form a striking instance of the Crocodilian affinities 
of the ILeamington fossil, yet as these detached superficial bones are 
the most liable to be separated from the fragmentary skeleton of the 
individual they once clothed, the negative fact of their not having 
been found associated with the remains of the Labyrinthodon in 
_ other localities proves nothing in regard to a difference of dermal 
structure between the Leamington and Warwick species. Indeed 
no anatomist, he says, can contemplate the extensive development 
and bold sculpturing of the dermal surface of cranial bones in the 
Labyrinthodon pachygnathus and L. leptognathus without a suspi- 
cion, that the same character may have been manifested in bony 
plates of the skin in other parts of the body. Admitting for a 
moment this structure to be proved, to what extent, asks Mr. 
Owen, does it affect the claims of the Labyrinthodon to be admitted 
into the order of Batrachians in which every known species is 
covered with a soft, lubricous and naked integument, without scales 
or scutze? In reply, he says, that the skin is the seat of variable 
characters in all animals; and, apart from the modifications of the 
osseous and dental systems, and other intimate organs, is apt to 
mislead the naturalist who is inquest of the real affinities of a 
species: and he instances the Trionyx, as an example of a soft- 
skinned animal among Chelonian reptiles. Lastly, Mr. Owen 
shows, that, previously to the discovery of the fossils described in 
this memoir, the only Batrachian remains which had been found in 
beds anterior to the epech of the Molasse is the fragment of a 
skull, on which Prof. Jaéger founded his Salamandroides giganteus. 
