File:The Quarterly journal of the Geological Society of London (13204945285).jpg

52 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY.
and laterad extension of the scapula corresponding to the blade of
the scapula of other vertebrates, which he considers to be absent in
Plesiosaurus.
Kecapitulated in the order in which they were enunciated, the
generic characters of Pliosaurus are those furnished, 1, by the pro-
podials (femora or humeri) ; 2, by the cervical vertebras ; 3, by the
teeth ; 4, by the cnemial or antibrachial (epipodial, 0. C. Marsh) seg-
ment of the limbs ; and, 5, by the " sterno-coraco-scapular frame."
In estimating the generic value of these several characters, it
should be borne in mind that no evidence is adduced that any of
the remains on which they were based were found so associated as
to warrant the belief that they formed parts of the same skeleton ;
indeed circumstances show that such was not the case. This is
certainly true of the two type femora of Pliosaurus grandis and P.
trochanter ius, of the paddle of P. jportlandicus, of the sterno-coraco-
scapular frame, and, I think, also of the vertebras and teeth. It
should also be mentioned that the two fine skulls presented to the
British Museum by J. C. Mansel-Pleydell, Esq., and referred by Prof.
Owen to Pliosaurus grandis and P. trochanterius, are dissociated
fossils.
It is evident that a series of generic characters drawn from such
dissociated remains can have only a hypothetical value.
Fig. 7. — Hind limb of Plesiosaurus Manseli.