five inches long. It has teeth which closely resemble those of 
Acanthopholis and Scelidosawrits. There was no evidence of 
the stratigraphical position of the fossil other than the matrix 
in which it was contained which resembled Calcareous Grit, 
and a fossil within it which is a typical example of the variety 
of Pecten vagaus , named P. fibrosus. On this evidence 
Professor Judd, F.R.S., and Mr. R. Etheridge, F.R.S., at the 
time the paper was read, suggested that the fossil was from the 
Calcareous Grit of Yorkshire. The specimen, now in the 
Woodwardian Museum, was formerly in the collection of the 
late Dr. Forbes Young, whose executors presented it to the 
University of Cambridge in 1861, but I am unable to trace 
its earlier history. It is possible that it may be a portion of 
the head of the Slingsby reptile. It is almost exactly of the 
size; and has the tooth character which such a specimen 
should exhibit; and the matrix favours the identification. If 
this suggestion should be supported by further evidence, the 
name Pnodontocj na thus may take precedence of Omosaurus , 
as having been founded on cranial characters, though both 
were proposed in the same year. As the name Omosaurus has 
been objected to by some writers as preoccupied by Leidy, it 
may be convenient to mention that Omosaurus perplexus 
(Leidy) 1856 (Proc. Acad. Nat. Sci. Philad. viii.) was founded 
on remains from the coal field of Chatham Countv, North 
Carolina, with teeth of varied type, biconcave vertebrae much 
constricted as in Palceosaurus and Clepsysaurus; and the animal 
is classed as an Fnaliosaurian. I am not aware that either 
Leidy or anyone else has fully described or figured it. Hence if 
the Omosaurus (Owen) of 1875 is a synonym of Priodontognathui 
there may be an advantage in retaining the latter name. In 
the belief that this identification is likely to be made, I suggest 
for the femur the name Omosaurus Phillip si because the jaw is 
already named Priodontognathus PhilHpsi. 
I am glad to have this opportunity of expressing my thanks 
to Mr. J. F. Walker, M.A., F.G.S., for the opportunity of 
studying this specimen ; and I desire also to acknowledge the 
aid in my examination obligingly given by Mr. Platnauer. 
I trust the interest which centres round this specimen may 
result in the discovery of other evidences of the animal to 
which it belonged. 
