Geological Society of London. 39 
Survey Memoir, in which, moreover, the subject of the old rocks 
under London will be treated somewhat fully. 
The following communications were read :— 
1. ‘Notes on the Remains and Affinities of five Genera of Meso- 
zoic Reptiles.” By R. Lydekker, Esq., B.A., F.G.S. 
This paper was divided into five sections. In the first the author 
described the dorsal vertebra of a small Dinosaur from the Cambridge 
Greensand, which he regarded as probably identical with the genus 
Syngonosaurus, Seeley. Reasons were then given for regarding this 
form as being a member of the Scelidosauride, stress being laid on 
the absence of a costal facet on the centrum. 
The second section described an axis vertebra from the Wealden 
of the Isle of Wight, which is evidently Dinosaurian, and may possibly 
belong to Megalosaurus. It is remarkable for exhibiting an inter- 
centrum on its anterior aspect, and also for the absence of anchylosis 
between its centrum and that of the atlas. 
In the third section the femur of a small Iguanodont from the 
Oxford Clay, in the possession of A. R. Leeds, Esq., was described. 
This specimen agrees with Hypsilophodon and Camptosaurus in its 
pendent inner trochanter, and it was referred to the latter genus as 
C. Leedsi. It is also considered to be closely allied to Iguanodon 
Prestwichi—the type of Cumnoria of Seeley —which is also considered 
to belong to the American genus. The name Camptosaurus valdensis 
was applied to an allied form from the Wealden; and the name 
Cryptodraco proposed to replace Cryptosaurus. 
The imperfect skeleton of a Sauropterygian from the Oxford Clay 
near Bedford, which formed the subject of a previous communication, 
was redescribed. This specimen was identified with Plesiosaurus 
philarchus, Seeley, which it was proposed to refer to a new genus 
under the name of Peloneustus. This genus was shown to be allied 
to Pliosaurus, and to be represented by forms in the Kimmeridge 
Clay which have been described as Plesiosaurus equalis and P. ste- 
nodirus. It was also compared with the genus Thaumatosaurus, 
Meyer, from which Rhomaleosaurus of Seeley was considered in- 
separable. Some remarks are added on other Sauropterygians; and 
it was proposed to adopt the name Cimoliosaurus for all the forms 
having a pectoral girdle of the type described under the names of 
Elasmosaurus and Colymbosaurus, and with single costal facets to 
the cervical vertebra. 
The paper concluded with a notice of the affinities of the Croco- 
dilian genus Geosaurus. This form was shown to be closely allied to 
Metriorhynchus, both being characterized by the absence of dermal ~ 
scutes and the presence of bony plates in the sclerotic. It was also 
shown that some of the species of Cricosaurus belong to the former 
genus; while there appear to be no grounds by which Dacosaurus 
(Plesiosuchus) can be separated from the same. 
2. “Notes on the Radiolaria of the London Clay.” By W. H. 
Shrubsole, Esq., F.G.S. 
Microscopical examination of the London Clay of Sheppey and 
elsewhere has afforded proof of the existence of a Diatomaceous zone 
