188 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



It may be as well to state that M^e have accepted the view that 

 the Weybourn Crag and Forest Bed series are not pliocene, hut 

 pleistocene. This opinion is almost universally held on the continent, 

 but it has not been widely adopted in this country, although the 

 evidence is, we venture to think, all in favour of this conclusion. 



In the determination of the species allowance has been made for 

 variation in the past, and in this way unnecessary additions, as we 

 deem them, to already overburdened lists are avoided. In those 

 cases where it has been impossible to trace the specimens, and there 

 is no inherent improbability of the correctness of their identification, 

 the species are cited on the authority of their recorder. 



Doubts have been expressed as to the true pliocene age of the 

 land-shells from Biitley, but these doubts, we consider, have no 

 foundation ; and it may here be mentioned that during a visit to the 

 Neutral Farm pit by one of us last June, three examples of Limncea 

 truncatula and one of Plcmorhis marginatus were obtained, whilst 

 more recently Mr. H. W. Eurrows has also obtained these same species 

 at that spot, and Mr. R. Holland has been fortunate enough to find 

 a good example of Hygromia hispida. The records of foreign occur- 

 rences are mainly on the authority of the late Dr. C. L. F. Sandberger 

 ("Die Land- uud Siisswasser Conchylien der Vorwelt"), and are 

 confined to those citations under the names employed in this paper. 



The first notice of the occurrence of non-marine mollusca in the 

 pliocene deposits of this country was by Samuel Woodward, the 

 Norfolk geologist, who in 1833 figured four species from the Norwich 

 Crag (1). In 1839 Sir Charles Lyell listed twenty-one species, on the 

 authority of S. Y. Wood, G. B. Sowerby and himself (2), these also 

 being all from the Norwich Crag, with the note that one form, Planorhis 

 marginatus, likewise occurred in the Red Crag. Mr. S. Y. Wood in 1842 

 enumerated eleven species, of which two Avere from the Red Crag (3). 

 The first part of that author's Monograph of the Crag Mollusca, 

 containing the Gastropoda, was published in 1848, and seventeen 

 species were there given (4). The volume containing the Pelecypoda 

 was issued in three parts — the first appearing in 1851, the second 

 in 1853, and the third in 1857 (5). Three additional species were 

 listed, thus raising the total to twenty. Nineteen species from the 

 Norwich Crag alone were next recorded by S. P. Woodward (6) 

 in 1864. In 1869 Mr. Alfred Bell enumerated four species 

 from the Red Crag of Butley (7), and in 1870 he added another, 

 Hygromia Mspida (8). In the following year he noted Limnma 

 palustris as also occurring there (9), and also recorded two forms 

 from Waldringfield and one from Walton (10). In 1871, too, 

 appeared the important papers by the late Sir Joseph Prestwich, and 

 lists of the non - marine species from the Red and the Norwich 

 Crags, on the authority of Gwyn Jeffreys, were given, the former 

 containing nine and the latter twenty-one species, eight being common 

 to both (11). In 1872 Alfred & Robert Bell published the result of 

 their researches, giving a list of thirty species (12). The same year 

 saw the issue of the first part of the supplement to Wood's Monograph 

 of the Crag Mollusca, the completion not being published tiU 1874, 



