R. Lydekker—Nomenclature of Fossil Reptilia. 329 
and to the misleading influence of old theories of metamorphism, 
very substantial results have been gained. I believe I am correct in 
saying that all who have studied the question with any degree of 
thoroughness, that is to say, in more than one or two localities, have 
come to substantially the same conclusion. Whether there are one, 
two, or three Archean systems—whether, if there are more than 
one, they are separated by broad or narrow gaps—are questions on 
which unanimity is not yet attained; but there is little difference 
of opinion as to the existence and distribution of the Archzean masses 
as a whole. The dynamic theory of metamorphism affects certain 
details of the Older Archeeans, it renders correlation amongst igneo- 
metamorphic masses somewhat less precise, and it materially alters 
all the old views on the Hastern gneiss of Sutherland. On the other 
hand, it opens up questions of the greatest interest, and renders com- 
paratively intelligible some of the earliest chapters in the earth’s 
history. 
VII.—Norte on some Points 1n THE NomMENCLATURE OF FossIL 
REPTILES AND AMPHIBIANS, WITH PRELIMINARY Notices oF Two 
New SpPEciEs. 
By R. Lyprexxer, B.A., F.G.S., F.Z.8. 
AVING occasion in a work now in the press to refer to certain 
A fossil Reptiles and Amphibians of which the commonly accepted 
nomenclature requires revision, I think it advisable to make the 
necessary amendments in a Journal specially devoted to Geology and 
Paleontology. I also take the opportunity of giving two new 
scientific names to Reptiles from the Wealden. 
The name Diplovertebron, Fritsch, as being a hybrid word, may 
be amended to Diplospondylus. Notochelys, Owen, being preoccupied 
by Gray, may be changed to Notochelone. 
Since there is every probability that Ornithopsis Hulkei, Seeley, 
is identical with Hoplosaurus armatus, Gervais, while the latter is 
probably not generically separable from the earlier Pelorosaurus, I 
propose to adopt the name Pelorosaurus armatus for the Isle of 
Wight species, on the assumption that it is distinct from P. Cony- 
beart of Sussex. The Kimeridgian and Oxfordian species described 
as Ornithopsis may likewise be referred to Pelorosaurus. 
The teeth from the Wealden provisionally referred by Mantell 
and Owen to Hylgosaurus are now known to be Sauropodous, and 
since they appear to be too small to belong to any of the described 
Wealden forms of that group, I propose to refer them provisionally, 
on account of their small size, to the genus Pleurocelus, Marsh, 
with the name P. valdensis. I am confirmed in this reference by 
a small dorsal vertebra in the British Museum (No. R. 1626), from 
the same deposit, which closely resembles that of the typical 
American species, and probably belongs to the same form as the 
teeth. 
Finally, I propose the name Megalosaurus Oweni for the meta- 
tarsus from the Wealden figured by Owen in his ‘ Wealden and 
Purbeck Reptilia,’ pt. iv. pl. xi. as Hyleosaurus, and referred by 
