OF THE UPPER CRETACEOUS IX WEST SETEOEE: AXT) XOREOEK. Oi i 



rare in Xorfolk that we only found the typical form in the pit at 

 Snettiskam, that in the Hunstanton " sponge-bed" being a fine-ribbed 

 variety, having some afhiiitv with Hh. lineolatd. 



The same is the case with Ammonites vavians, which is so 

 common a fossil in the Chalk-marl of lieach and other Cambridge 

 localities, and which is still abundant in the hard marl of Hockwold 

 Grange, Suffolk. At Stoke Ferry it is a rare fossil, and beyond that 

 place we did not meet with it at all except doubtfully at Hunstanton, 

 neither is it recorded in Dr. Barrois's lists, so that if it does occur 

 it is one of the rarest fossils at Hunstanton. The same may be said 

 of Ammonites Alantelli, which is common in the Chalk-marl of the 

 southern counties, but becomes rarer in going north. 



It would' appear in fact that the Ammonites were inhabitants of 

 shallow waters, for while the}' swarm in the Gault, ITpper Greensand, 

 and Chalk-marl of the southern counties, they become gradually 

 less abundant in the higher parts of the chalk of that region. 

 Since therefore they also become much rarer both in the Gault and 

 in the Chalk- marl as these divisions are traced northward, we 

 may reasonably conclude that this rarity is due to the increase in 

 the depth of the Cretaceous sea towards the north, an inference 

 already drawn from other data. 



We have to thank Mr. H. G. Fordham for the loan of the fossils 

 which he collected recently from the Sponge-bed at Hunstanton ; 

 these have enabled us to give a fuller list than has hitherto been 

 published. One of the commonest fossils in this bed is Avicala 

 grypkczoides, which is so abundant in the basement -bed at Eoyclon 

 and Shouliham and in the Cambridge Greensand ; this species occurs 

 rarely in the Inocerarnas-be&s, and we did not meet with it above 

 that horizon. 



Our thanks are also due to Dr. G. J. Hinde for naming the 

 fragments of Sponges which Air. Fordham had found. 



Taeee III. — Fossils of tJie ToiUrnlioe Stone. 



ECHIXODERAIATA. 



Holaster subglobo^us, Leske 



Discoidea cylindrica, Lam 



Cidaris vesiculosa, Goldf. (spines) 



Crustacea, &c. 



Veruiicularia umbonata, Sby 



Pollicipes glaber, Rom 



Scalpelium maximum, Sby 



GTyphea cretacea, M'Coy 



Euoploclytia breviniana, M'Coy ... 



— 



© 

 O 



S3 



55 



U2 



