R. Lydekker—Catalogue of Fossil Reptilia, ete. 453 
It is not improbable that the mandibular ramus entered on p. 227 
as a young Iguanodont may really indicate a smaller adult form 
allied to Laosaurus or Camptonotus, in which event the undetermined 
femur mentioned on p. 195 may perhaps belong to the same form. I 
am also inclining to the opinion which was suggested in the Catalogue, 
that some of the portions of pectoral and pelvic girdles entered under 
the head of Iguanodon Bernissartensis may indicate a second large 
species of Wealden Jguanodont. 
I am further indebted to Prof. Marsh for pointing out that the 
name Omosaurus is preoccupied by Leidy (Proc. Ac. Nat. Sci. Phila. 
1856, p. 256). Since, however, the form so designated is known 
only by the preliminary description, I do not intend to propose a 
new name; more especially since I think it not improbable that 
Stegosaurus is generically inseparable from Omosaurus, in which 
case the former name should be adopted. 
Turning to the Enaliosaurians, Prof. Marsh informs me that 
Baptanodon shows no trace even of a dental groove, and it would there- 
fore seem that Dr. Baur’s suggestion as to the generic unity of this 
form with Ophthalmosaurus is not well founded. 
In regard to Plesiosaurus Oxoniensis (supra, p. 352), a visit to the 
Oxford Museum, where I have seen the whole of the type-specimens, 
has shown that the skeletons in Mr. Leeds’ collection indicate a form 
so much superior in size to the type of that species, that I am 
inclined to think it will be safe for the present to retain for them 
the name of P. eurymerus, although I can see no structural difference 
in the vertebree. Both the pectoral girdle and the limb-bones figured 
by Phillips under the former name are from a different locality from 
the vertebral column, and I now think are probably both referable 
to P. plicatus. This pectoral girdle when entire was of the type of 
that of the so-called Klasmosaurus. In these notes I have used the 
term Plesiosaurus in its wider sense. With regard to P. philarchus, 
which I was inclined to include in Thaumatosaurus, I have since seen 
reasons which have induced me to regard this form as indicating a 
new genus connecting Thaumatosaurus with Pliosaurus. 
Finally, I must offer my apologies to Prof. Cope for the statement 
regarding Hlasmosaurus (supra, p. 356). In a separate copy in the 
Museum Library of the memoir to which I have alluded the figure 
of the skeleton is given in the reversed manner I have mentioned. 
This copy belongs, however, to an advance issue, of which, I am 
informed, the greater portion was suppressed, and in the serial 
itself the erroneous restoration and the accompanying letterpress 
have been amended. 
V.—Awn UnpusoriBep CarBoniIFERous Fossit. 
By Prof. T. Ruprerr Jones, F.R.S., and Dr. Hy. Woopwarp, F.R.S. 
N the Museum of Practical Geology, London, is a remarkable 
specimen, marked D 4,6, which the late Mr. J. W. Salter referred . 
to, in the ‘ Quart. Journ. Geol. Soe.’ vol. xix. 1863, p. 92, as ‘a huge 
bivalve Crustacean,” . . . “with a carapace 7 inches long,” giving 
it the name “ Dithyrocaris pholadomya.” It is in a dark micaceous 
