A. 8. Woodward—British Jurassic Fishes. 453 
of these are about 3in. (0-075 m.) in length, and 4in. (0-010m.) in 
width. Hach is laterally compressed, slightly expanded at one 
extremity, and rarely straight, but irregularly bent or contorted. 
The surface is coarsely rugose, and one long border is rounded, 
while the other is cleft by a longitudinal median furrow. The 
rounded border is comparatively smooth, but the furrowed edge is 
coarsely serrated, a series of short oblique ridges terminating in 
points on each side. 
6. Portion of a large squamous bone, longer (deeper) than broad, 
with one long margin thickened, rounded, and concavely arched. A 
nearly complete example of the same element, doubtfully forming 
part of the series, measures 2ft. 9in. (0°838m.) in length, and suggests 
that it may be identified either with the preoperculum or clavicle. 
7. Portions of eleven very dense, large, rib-shaped bones, only 
superficially ossified at the broader extremity, but terminating in a 
well-formed point at the distal end. These bones are rounded or 
irregularly quadrangular in section, are more or less arched, and 
vary considerably in relative width or thickness. The broadest and 
stoutest specimen is much arched, 1 ft. 5in. (0°48 m.) in length; and 
a nearly perfect detached example of the same bone shows that this 
wants a length of at least Sin (0:23m.) at the pointed extremity. 
The largest bone measures 2ft. 4in. (0°712m.) in length, and is 
straightened ; while the smaller examples are more curved and more 
rounded in section. These bones were evidently arranged in not 
less than six pairs, and Mr. Leeds’ suggestion seems most plausible, 
that they are the branchiostegal rays of the fish. 
8. The fin-rays are most remarkable, and, judging from the 
position in which they were discovered, the known specimens may 
all probably be assigned to the pectoral fin. They consist of fibrous 
bone, and appear as if composed of numerous long, tapering bony 
splints, incompletely fused together. 'The two halves of each ray 
remain separate, and in some cases they have been proved to attain 
a length of not less than 5ft. (1:525m.). There are no transverse 
joints, but all the rays exhibit numerous bifurcations, and Mr. Leeds 
estimates that the distal extremity of each of the largest becomes 
divided into at least thirty-two small branches. 
Smaller more slender fin-rays, probably of the same type of fish, 
have also been discovered in the Oxford Clay of the same locality. 
These are gently rounded and transversely articulated, thus suggest- 
ing that the specimens just noticed are characteristic only of a 
powerful pectoral. 
As already mentioned, many other detached bones, undoubtedly of 
the same genus and species, occur in Mr. Leeds’ collection; but, of 
the elements not described above, the form is so indefinite as to 
render their determination very uncertain. If, however, the few 
suggestions here propounded are eventually confirmed, it is obvious 
that many hard parts of the fish still remain to be discovered. No 
known fish with ossifications of the branchial arches and branchi- 
ostegal membrane of the kind here described is destitute of at least 
some ossifications in the axial skeleton of the trunk; and it will be 
strange, indeed, if a monster with such powerful pectoral fins does 
