144 Correspondence — Mr. W. J. SoUas. 



described the matrix as a fine chalky marl, full of Foraminifera, and 

 minute fragments of organisms, with a considerable mixture of mud, 

 insoluble in hydrochloric acid. The composition of the green 

 grains (commonly called Glauconite) was then discussed, and it was 

 shown that they differed considerably from the typical mineral of 

 that name ; he had not satisfied himself that any were casts of 

 Foraminifera. After a few words on the phosphatic nodules and 

 some erratic rocks in the bed, he gave a sketch of the paleontology 

 of the deposits; calling attention to the condition of the various 

 fossil remains, and to the number and size of the Pterodactyles and 

 Turtles. He then gave his reasons for considering this deposit as 

 formed during the Upper Greensand Epoch, but as containing many 

 fossils which had been derived from the Upper Gault by slow 

 denudation. The nodules he considered as mainly of concretionary 

 origin ; for they were too pure to be regarded as clay saturated by 

 phosphate. He concluded by sketching out his conception of the 

 physical geography of the East Anglian district in the Neocomian 

 and lower part of the Cretaceous epoch. — Professor Morris, after 

 some remarks on the value of the paper, spoke of the composition 

 of the green grains, and then traced the range of the deposit, which 

 he agreed with Mr. Bonney in thinking was the formation of a very 

 long period of time. — Mr. Lobley remarked upon the mineralogical 

 and palgeontological differences existing between the Cambridge 

 deposit and the Chloritic Marl of Dorsetshire.— Mr. Bonney, in his 

 reply, having referred to the great scarcity of fossils in the Gault of 

 Cambridge, the Eev. T. Wiltshire stated that the Gault of Kent was 

 in some places devoid of organisms. — At the next meeting of the 

 Association, Friday, 1st March, a paper will be read ''On the 

 Geology of Hampstead, Middlesex," by Caleb Evans, Esq., F.G.S. 



COI^E-ESI'OlsrDEIiTOIE]. 



NEW BRITISH CRUSTACEAN. 

 giK —■Will you allow me to record tlie occurrence of Gastrosacus Wetzleri, -whicli 

 I have found in tlie so-called Coral Rag of Upware, Cambridgeshire. This, the only 

 species of its genus, is found in the White Jura of Bavaria, and has not hitherto been 

 met with in Britain. ttt t <n 



St. John's College, Cambridge, W . JoHNSON SoLLAS. 



21 th December, 1871. 



CALCAREOUSLY-INCRUSTED STONES IN DRIFT. 



gjjj^ As your obliging statement, at the close of my last article, relative to the 



inoro-a'nic origin of incrustations on stones found in the Upper Boulder-clay of 

 Cheshire, might by some readers be regarded as bearing on the general arguments 

 contained in the article, would you allow me to say that my reference to these stones 

 (on which I did not venture to express a decided opinion) was extraneous to the main sub- 

 ject of the article, and that my object in making it was not to prove the marine origin of 

 the Upper-clay (which is now admitted by all geologists), but to try to discover some 

 resemblance between this clay and the brick-clay of Scotland, in which, in some 

 places, organically-incrusted stones are common, according to Mr. Jamieson. I hope 

 Mr. James Geikie will soon be able to correlate the Scotch and English drifts. I 

 have no doubt that my Finel is the equivalent of his Till. 



D. Mackintosh. 



