File:The Quarterly journal of the Geological Society of London (12645660465).jpg

1862..
HTJXLEY CARBONIFEROUS LABYRINTHODONT.
63
field and then described, were necessarily Ichthyosaurian, — seeing
that I had mnch reason to suspect that they might belong either to
Labyrinthodonts, or to some genus of intermediate characters, be-
tween Labyrinthodonts and Ichthyosaurians.
"Within the last few days Mr. Russell has sent me the vertebra of
which an outline-view is given in fig. 2 (one-half the natural size).
It was found in the same bed as that which yielded the skull of
Anthracosaurus, and corresponds very well in size with what one
might expect would be the dimensions of a dorsal vertebra of that
animal. Associated with it on the same slab are several other less
complete vertebraa and the remains of two ribs.
Fig. 2.
A. Dorsal vertebra of Anthracosaurus, viewed from behind.
B. Rib of the same Amphibian.
A.
i.
A.-
B.-
Body of the vertebra.
The longer division of the transverse process, and
The shorter division. /. Spinous process.
Anterior zygapophysis. g. Neural canal.
Posterior zygapophysis.
Capitulum. b. Tuberculum.
The body of the vertebra is greatly flattened from before back-
wards, as the subjoined measurements will show. The exposed
articular surface is concave, and a section which I have had made of
a similar vertebral body shows that it was equally concave upon both
sides. The concavity, however, is not conical in section like that of
a fish's vertebra, but its sides are a little convex, rising slightly, within
the margin. Hence the section of this vertebra has very much the
same appearance as that of Mr. Marsh's problematical vertebra repre-
sented in the figure which accompanies his paper*.
The contour of the vertebral body is not circular, but is slightly
angulated, so that it would tend to be octagonal were not the place of

• Am. Journ. Science, n. s., vol. xxxiv. pi. 2. fig. 2.