364- Mr. Lyell on the Boulder Formation, 



var. o^ amnicum. The shell appears to be rather thicker than 

 the recent P. amnicum, and the teeth stronger : see fig. 1 1 . 



Fiir. 11. 



Cyclas {Pisidiurn) amnica, var. ? 



From the freshwater beds at Runton. The two middle figures are of the natural 



size. 



Neither here nor at Mundesley was I able to find Cyrena 

 trigonula^ which however we might have expected to discover 

 in these beds, as it accompanies a similar assemblage of shells 

 from various localities in Suffolk and Essex. 



I found no remains of insects in the black earth, but the 

 Hon. and Rev. R. Wilson, of Ashwell Thorpe, showed me in 

 his collection, in 1838, the elytra of beetles of the genus Do- 

 nacia^ preserving their colours, which he had found several 

 years before at Runton. I observed the scales of perch and 

 of other fish resembling those of Mundesley in the black earth. 

 Mr. Simons has also found fragments of the scapula and horns 

 of a deer in the black earth. 



In general it is most difficult to speak with certainty re- 

 specting the position of fossil bones of quadrupeds derived 

 from the mud cliffs, because they have been picked up at the 

 base of the cliff after portions of it had been washed away by 

 the sea. It is the opinion, however, of collectors that they 

 are chiefly derived from strata, in which the lignite and sub- 

 merged trees occur. The remains are those of the elephant, 

 rhinoceros, hippopotamus, horse, ox, pig, beaver, deer, &c. 

 At Cromer and Weybourne some mammalian bones occur in 

 the crag, but they are commonly more rolled and worn than 

 those derived from the lignite deposits. Unfortunately no 

 freshwater shells have yet been obtained from precisely the 

 same bed as that in which the bones of the elephant and 

 other extinct quadrupeds are met with, nor from the stratum 

 in which the stools of buried trees are enveloped. The fresh- 

 water shells of Mundesley and Runton, although they may 

 probably belong to the same formation, are not yet proved to 

 be strictly coeval with the extinct quadrupeds. The present 

 state, therefore, of our knowledge would not enable us to enter 

 into minute details in regard to the order of superposition of 

 the beds between the chalk and drift in tlie mud cliffs, but it 

 would appear that the principal site of the bones of extinct 

 mammalia as well as of the buried forest and lignite is be- 



