A-^D CLASSIFICATION OP THE FOSSIL REPTILIA. 
2Iio 
Fihula of Titanosuclius fevox. (Plate 21.) 
Pight fibula.—A bone whicli was broken in two and has been restored exhibits a 
flattened hour-glass-like form, with oblique articular ends, a concave internal contour 
which shows a flattened ovate surface proximally, presumably for contact with the 
tibia, though a similar surface exists on the proximal end of the radius in No. 3<3,259, 
named Dicynodon tigriceps (Owen.) The external contour is so much less concave as 
to be almost straight. The extreme length of the bone is about 29 centims., so that 
it was less than half as long as the femur. This is exactly the proportion in the giant 
Salamanders of Japan, and establishes the Amphibian proportions of the limbs in 
Titanosuclius fevox. 
The proximal end is 12‘5 centims. broad, and may have been as thick as the distal 
end, but the external surface of the proximal end is broken away. It appears to have 
been transversely ovate and convexly rounded. The inferior surface of the shaft is 
flattened transversely, but still is a little convex, while it is markedly concave in 
length. The transverse measurement in the middle of the shaft is less than 9 centim.s., 
and the thickness is there reduced to 5'5 centims. ; but, distally, the bone expands 
in both dimensions. Its transverse width at the distal surface, which is imperfect 
towards the tibia, does not appear to have exceeded 12 centims., while its thickness 
may have been 11 centims. Its outline is sub-ovate. The articular surface is flattened 
in the antero-posterior direction, and oblique and convex from the tibial margin 
downward and outward. There is some appearance of the surface towards the tibia 
I)eing inclined more obliquely inward, as though it had helped to support a tarsal bone 
which was lodged between the tibia and fibula. The distal end is greatly thickened 
on the inner side of the shaft. All the surfaces of the shaft are well rounded in the 
transverse direction, and moderately concave in the vertical direction. 
The Ulna. (Plates 22 and 23.) 
Besides the ulna, No. 43,525, catalogued by Sir P. Owen as the right ulna of 
Pareiasaurus homhidens, there are two smaller specimens in the British Museum, 
registered respectively as No. 36,249 and No. 49,389. Taken in connection with the 
other specimens, these isolated examples demonstrate the nature and development of 
the epiphyses, and prove these elements of the bone to have been quite as large and 
as well developed in Anomodonts as in Urodeles, as far as external contour is 
concerned, for there is no trace of the epiphysial element having penetrated the 
shaft. Proximally, the fully ossified ulna is prolonged in a massive olecranon process, 
and this ossification included the whole of the concave articular surface. In the 
specimen 49,389, which was forwarded by Mr. Bain with many bones which were 
referred to Dicynodon tigriceps, the surface is seen from which the epiphysis has come 
away ; and it proves to be convex, and so even that the extent of tbe epiphysis it 
MDCCCLXXXIX.- n. 2 M 
