254 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [Maich 20, 



a large river rather than with inland lakes. These, from time to 

 time, owing to oscillations of level, were covered with marine 

 deposits. He did not think that the absence of gravelly deposits 

 offered any serious difficulty in regarding the "Wealden strata as 

 having been formed at the mouth of a large river. It seemed 

 to him probable that the sands and clays of the Wealden were 

 due to ancient rivers on a large scale, though in some spots the 

 beds were subject to the action of fresh and salt water alternately. 

 To the east of Oxford the Lower Greensand beds were found at first 

 to contain marine shells ; but as they proceeded eastward fresh- 

 water forms made their appearance, and in places at last predomi- 

 nated in beds of the same lithological character He regarded the 

 Neocomian as, to some extent, a marine representative of the 

 Wealden, though of later date. 



Mr. Etheridge recalled the fact that Mr. Judd had correlated the 

 Punfield fossils with those of the north of Spain, twenty-two species 

 found in each being absolutely identical. He argued from this that 

 the extent of the beds may have been far larger than might be sup- 

 posed. In Hanover beds, characterized by different Ammonites, 

 occurred in precisely the same order as in England at Speeton and 

 elsewhere. He regarded the question between Mr. Judd and the 

 author of the paper as not yet absolutely settled, though both had 

 done much for its elucidation. 



Prof. T. RtrpEKT Jones remarked that the Purbeck- Wealden lake 

 theory had not only been intimated by several previous writers, but 

 had been illustrated by maps by Messrs. Godwin- Austen and Searles 

 Wood, Jun. Whatever the direction of the main rivers, and what- 

 ever the extent of the lakes, the Eev. Osmond Fisher had shown 

 that one river came in from the west. Mr. Jones instanced, in 

 reference to the lake theory, the occurrence of Oysters, Potamides, 

 and Corbulce in the base of the Wealden at Poundsford — also that of 

 the dwarf TornateUa Popei at Tunbridge Wells and Balcombe. He 

 alluded also to the brecciated condition of some and the upturned 

 position of other Wealden beds. In alkision to the small bivalve 

 Entomostraca so often referred to, he regretted that they had not 

 yet been fully described; a bed of them occurs in the Upper 

 Portland at Hartwell before the Purbeck sets in. He concluded by 

 sajdng that such general papers as the one under discussion ought 

 to have detailed references to the writings and opinions of previous 

 observers. 



Mr. HiTLKE referred to the question of gravels being present in 

 the Wealden, and stated that these were in some localities abundant, 

 getting coarser in the beds furthest to the west. This increase in 

 the coarseness of the gravel was suggestive of a river running from 

 west to east. In the east of the Isle of Wight he had found remains 

 of Plesiosaurus, a marine form, much more commonly than fiirther 

 west, which supported the same view. He mentioned beds between 

 Brixton and Calbourne, in the Isle of Wight, which appeared to him 

 strictly analogous to those in Worborrow Bay. 



Mr. Jenkins disputed the identity of origin of the Purbeck and 



