TRANSACTIONS OF THE SECTIONS. 



85 



The author in the next place proceeds to discuss the relation which 

 this mammiferous stratum bears to the two tertiary deposits of the ad- 

 joining county, showing that it is not, as he had anticipated, an exten- 

 sion of the red crag of Suffolk, but a deposit altogether distinct from 

 it and the coralline, differing essentially from both in the number and 

 nature of its organic contents. Its geographical limits are not confined 

 to Norfolk, since it may be traced from Norwich to Aldeburgh in Suf- 

 folk, overlying some part of the coral reefs in that most interesting 

 locality. It may be most advantageously examined in the immediate 

 neighbourhood of Norwich ; at Southwold, and on Thorp Common near 

 Aldeburgh. This stratum as regards relative age may be looked upon as 

 holding a station intermediate to the red crag, and those deposits in 

 which the testacea appear to belong almost exclusively to existing species 

 of mollusca. 



The beds above the chalk in Norfolk, Suffolk, and Essex may be 

 grouped into two sections, determined by the presence of terrestrial 

 mammalia throughout a part of the series, which in descending order 

 will be as follows : — 



1. Superficial gravel, containing bones of land animals, pro-") i 

 bably washed out of stratified deposits. 



2. Superficial marine deposits of clay, sand, &c., in which the 

 sheUs very few in number (10 or 15 species), may all be 

 identified with such as are now existing. 



Examples. — Brick earth of the Nar, Norfolk. 



3. Ruviatile and lacustrine deposits, containing a consider- 

 able number of land and freshwater shells, with a small 

 proportion of extinct species. (Mammalian remains in great 

 abundance.) 



Localities. — Ilford, Copford, and Grays in Essex. Stutton in 

 Suffolk. 



4. Mammiferous crag of Norfolk and Suffolk, hitherto con- 

 founded with red crag, containing about 80 species of 

 shells : proportion of extinct species undecided. 



Localities. — Bramerton near Norwich ; Southwold and Thorp 

 in Suffolk. J pq 



2 I 



5. Red crag, containing 150 to 200 species of shells : propor- ' 

 tion of extinct species undetermined. 



Localities. — Walton and Dovercourt, Essex ; Felixstow, New- 

 bourn, and Bawdesey, Suffolk. 



6. Coralline crag, containing 3 to 400 species of shells : pro- 

 portion of extinct species undetermined. 



Localities. — Ramsholt, Sutton, Tattingstone (beneath red 

 crag), Aldeburgh, Orford. 



7. London clay. 



8. Plastic clay. 



The author next adverts to the remains of birds which he has re- 

 cently obtained on several occasions in the mammiferous stratum of 



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