Seeley — Rock of the Cambridge Greenland. 307 



of lime, while a few with calcite shells, such as Ostrea, Nerita, etc., 

 are well preserved. Many of the casts are worn and often have 

 oysters and Plicatulce growing upon them, showing that the shells 

 were removed while the specimens rolled on the shore. 



Echinoderms, Crustacea, polyzoa, corals and sponges, all have a 

 fair proportion of species. But nearly everything is mineralized and 

 infiltrated with the phosphate, though small brachiopods, serpulee, 

 polyzoa and cirripedes have escaped. 



The only evidence of vegetable life on land is found in balls of 

 resin, of four or five different kinds, which burn with pungent fumes, 

 some of them having a plum-like smell. 



Such is the Cambridge Greensand in its aspect as a rock, a con- 

 sideration of which may pave the way for explaining how it came to 

 have its peculiar fauna ; for a knowledge of the origin of rocks is 

 the very hornbook of biology, both recent and fossil. 



IsTOTICES OIP nyLEDynoiK-s. 



I. — Phosphatic Nodules. 



AT a recent meeting of the "Bath Natural History and Antiqua- 

 rian Field-club," the President, theEev. L. Jenyns, M.A.,F.L.S., 

 F.G.S., delivered a lecture on the Phosphatic Nodules obtained in 

 the eastern counties for agricultural purposes. He treated the sub- 

 ject both in its geological and economic points of view. Phosphatic 

 nodules, erroneously called " coprolites," are worked most exten- 

 sively in the counties of Cambridge and Suffolk. The application 

 of them to Agricultural purposes is due to the scientific acumen 

 of the late Professor Henslow, who, while on a visit at Felixtow, 

 in 1842, noticed the occurrence of certain nodules or concretions in 

 the Eed Crag (which is largely developed there), and in a commu- 

 nication, read before the British Association in 1845, he suggested 

 the uses to which they might be put in agriculture. 



The phosphatic nodules of Cambridgeshire occur in the Upper 

 Greensand, forming a stratum generally from six to nine inches in 

 thickness, and extending over many miles in the vicinity of Cam- 

 bridge, they sometimes form an even layer on the Gault, but are not 

 unfrequently found in cavities hollowed out here and there on its 

 surface. 



The Suffolk nodules, obtained from the Eed Crag, are of rather 

 less value than those of Cambridgeshire, as they contain a smaller 

 percentage of phosphate of lime. They are similar to nodules oc- 

 curring in' the London clay, from which deposit they have been 

 derived. The Eocene nodules contain from 50 to 60 per cent, of 

 lime, while those from the Crag average about 53 per cent, of it, 

 with 13 per cent, of phosphate of iron as well as carbonate of lime 

 aaid volatile matter. 



With regard to the nodules from strata in other counties, Mr. 



