CARBONIFEROUS LABYRINTHODONT 567 
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 
represented 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 the uppermost angle of the octagon occupied by the excavated 
floor of the neural caual. The short sides of the vertebral body are 
concave from before backwards, and in other specimens exhibit a 
slightly rugose marking. 
The neural arch is very small in proportion to the size of the body 
of the vertebra, and its contour is nearly that of an equilateral 
triangle with a curved base. 
The very stout sides of the neural arch are continued upwards into 
a strong spinous process, which is broken off a short distance above 
its origin and nearly on a level with the upper parts of the 
zygapophyses. Of the latter the posterior pair are turned towards the 
eye, and are much broken. The hinder face of the right anterior 
zygapophysis is visible (at @), and its curved contour is nearly entire. 
The transverse process of the right side (the only one preserved) 
springs by a long line of origin from the lower part of the neural arch 
and from the upper half of the circumference of the vertebral body. 
It is greatly flattened from before backwards, and its lower half (c) 
ends, at a distance nearly equal to half the diameter of the body of 
the vertebra, in a rounded edge, which appears to be complete and 
unbroken. The upper half, on the other hand, terminates in an 
obviously rough and fractured extremity. I conclude from this 
circumstance, and from the characters exhibited by the proximal ends 
of the ribs, which I shall immediately describe, that the upper division 
of the transverse process extended much further outward than the 
lower, and I have indicated this in the dotted restoration of the left 
side of the vertebra. 
inch. 
Height of body of vertebra ......-..- 1'6 
Transverse diameter... . eee eee eee 16 
Lene. sek adn a 258 eRe Ho a RS C47 
Height of neural arch ........ saya, w O38 
Depth of transverse process .....+-+- og 
Thickness of transverse process ... ... 0% 
1 Am. Journ. Science, n.s., vol. xxxiv. pl. 2. fig. z. 
