270 B. Lydehker and O. A. Boulenger — Notes on Chelonia. 



agent as the bedded deposits is shown in a figure on the next plate 

 of the same work, where a mass of Boulder-clay overlies such 

 materials in the ice. The moraine profonde (including under this 

 term all the drifts carried at and towards the base of the ice, whether 

 derived from upland districts, or caught up from an ancient sea-floor 

 over which the ice passed) coming from the flat tracts of the extreme 

 East of England and the North Sea would be driven through the 

 lateral valleys of the Sudbury area, and compressed laterally owing 

 to the smaller space necessarily occupied by the lower parts of the 

 ice under these circumstances. In this manner the contortion would 

 be produced, accompanied by the small faults which are so common 

 in these drifts, and so difficult to account for except upon the view 

 that the drifts were solid at the time of faulting. Upon the melting 

 of the ice, the drifts of this moraine, — Boulder-clays, gravel, and 

 loam, — would be left standing upon the undisturbed beds of the 

 irregular floor, once frozen, but resuming their incoherent condition 

 upon the passing away of the cold. 



In this way, and apparently in this way only, can we account for 

 the phenomena of the Sudbury district, and the explanation has the 

 advantage that it brings into play an agent which we know, from the 

 researches of the Danish explorers upon the Greenland ice, does 

 produce similar features at the present day, whereas all other 

 explanations require the operation of agents, whose asserted mode 

 of procedure is purely hypothetical. 



V. — Notes on Chelonia from the Pukbeok, Wealden and 



LONDON-CLAY. 

 By E. Lydekker B.A., F.G.S., and G. A. Boulenger, F.Z.S. 



Introductory. — The writers having had occasion, in company with 

 Mr. Davies, to examine the greater number of the remains of English 

 fossil Eraydine and Pleurodiran Chelonia in the collection of the 

 British Museum, with a view both to their rearrangement in the 

 cases and the determination of their affinities, and having in the 

 course of such examination been enabled to add several genera to 

 the British fauna, as well as to make certain emendations in regard 

 to the age and affinity of some of the previously-described forms, 

 have thought it advisable to put their observations on record. 

 Several of these observations are, indeed, only supplemental to those 

 already published by Prof. Ktitimeyer, of Basle, in the invaluable 

 memoirs quoted below, but the writers have been able in some 

 instances to add to his conclusions, owing to facts with which the 

 learned Professor was necessarily unacquainted. 



The reference by M. Dollo, of the Brussels Museum, of three of 

 the Lower Eocene English species described by Sir E. Owen under 

 the generic name of Chelone to a distinct genus Fachyrhynchus, has 

 been already noticed by one of the present writers in last year's 

 volume ^ of this Magazine. The term PachyrJiynchus is, however, 



1 Page 521. I must apologize to M. Dollo for having in this notice misinterpreted 

 him as retaining Prof. Cope's family Fropleuridm. In the same notice I have quoted 

 English forms under the generic names assigned to them by Owen, not having at that 

 time entered on the question of the correctness of their determinations. — [E. L.] 



