564 Reviews—Dr. Andrews’ Marine Reptiles, Ozford Clay. 
top of the Viséan there occurs a well-marked Cyathaxonia phase 
which is generally succeeded by the Posidonomya Becheri beds. In 
the typical Yoredale area the same succession has been observed at 
the base of the Yoredales. If the equivalence of the Lower Culm, 
Pendleside, and Yoredale Series be admitted, then a tripartite division 
of the Avonian is necessary, and for this upper division the work of 
Phillips in having pointed out the importance of the Yoredales as 
a distinct division of the Lower Carboniferous should be recognized, 
and the term Yoredalian employed in our proposed classification, shown 
on p. 663. 
It is obvious that with any classification there will be local 
difficulties. It is known that in some places the normal D, conditions 
persisted into Lower Yoredale time, or that it was replaced by 
a development of the ‘ knoll’ limestones. In other areas the 
Cyathaxonia phase is found intercalated with the Postdonomya Becheri 
beds. These difficulties are but local and do not affect the general 
applicability of the proposed classification. 
REVIEWS. 
——_@——_ 
I.—A Descrterive Caratocus or THE Marine Reprines oF THE 
Oxrorp CLAY, BASED on THE Lenps CoLtucrion in THE BritisH 
Museum (Narvurat History), Lonpow. Part I. By Carts 
Wittiam Anprews, D.Sc., F.R.S. 4to; pp. xxiii and 205, with 
frontispiece, 10 plates, and 94 text-figures. Printed by order of 
the Trustees of the British Museum, London, 1910. Price £1 5s. 
OR some years past visitors to the Natural History Branch of the 
British Museum at South Kensington, who have passed through 
the gallery devoted to fossil reptiles, cannot have failed to be 
attracted by certain specimens of Plesiosaurians which, on account 
of their perfect condition and the method of mounting, appear more 
like modern skeletons than the remains of ancient fossil creatures. 
These specimens, it is well known, form part of the famous Leeds 
Collection of fossils from the Oxford Clay of Fletton, near Peterborough. 
It was Dr. Henry Woodward, when Keeper of the Department, who 
first interested himself to obtain these remarkable specimens for the 
British Museum; and his successor, Dr. A. Smith Woodward, has 
been no less assiduous in securing this unique collection. 
It is now several years since the first of the skeletons was placed 
on view in the Museum cases, and it had been mounted most skilfully- 
and with great patience by the late Mr. C. Barlow. Several other 
examples have been added more recently, most skilfully set up by his 
son, Mr. F. O. Barlow, the present formatore. A careful examination 
of these specimens, even by those who are not specially interested 
in fossil reptiles, will prove of no little interest, especially if one 
bears in mind the amount of time, attention, and skill expended in 
bringing them into their present satisfactory condition. 
The greater number of the bones were obtained by Mr. Alf. N. 
Leeds, of Eyebury, Peterborough, during the last twenty years, 
but the collecting was begun much earlier by his brother, Mr. Chas. 
HE. Leeds. Mr. Leeds, living near the Oxford Clay pits at Fletton 
