CHAP. xii. MUNDESLEY FRESHWATER FORMATION. 225 



Mr. King. The last-named geologist has had the kindness 

 to draw up for me the annexed diagram of the various beds 

 which he has recently studied in detail.* 



The formations 3, 4, and 5, already described, p. 213, were 

 evidently once continuous, for they may be followed for. 

 miles NW. and SE. without a break, and always in the same 

 order. A valley or river channel was cut through them, pro 

 bably during the gradual upheaval of the country, and the 

 hollow became afterwards the receptacle of the comparatively 

 modern freshwater beds, A, B, c, and D. They may well re 

 present a silted up river-channel, which remained for a time 

 in the state of a lake or mere, and in which the black peaty 

 mass, B, accumulated by a very slow growth over the gravel 

 of the river-bed A. . In B, we find remains of some of the 

 same plants which were enumerated as common in the 

 ancient lignite in 3', such as the yellow water-lily and pond- 

 wort, together with some fresh water shells which occur in 

 the same fluvio-marine series 3'. 



Fig. 34 



Paludina marginata Michaud. (P. minuta Strickland.) 

 Hydrobia marginata.^ 



The middle figure is of the natural size. 



The only shell which I found not referable to a British spe 

 cies is the minute paludina, fig. 34, already alluded to, p. 1 64. 



* Mr. Prestwich has given a correct one, as in Paludina), and therefore to 

 account of this section in a paper read be referable to the Hydrobia, a sub- 

 to the British Association, Oxford, genus of Eissoa. But this species is 

 1860. See Geologist's Magazine, always associated with freshwater 

 vol. iv. 1861. shells, while the Kissose frequent 



f This shell is said to have a sub- marine and brackish waters. 

 spiral operculum (not a concentric 



