THE CORALLIAN ROCKS OF ENGLAND. 



271 



particular notice. A few feet from the top of the sand we find 

 a bed with Pinna pescilina in the position of life. Below this a 

 dark green rock comes on. Grit is certainly a chief component of 

 all these rocks ; but they are so coloured by iron in various com- 

 binations and states of oxidation, as to seem much richer in that 

 metal than they really are. The middle and lower portions are most 

 calcareous, and are specially remarkable for the strange interlacing 

 fucoid or sponge-growths, which are not only met with here and 

 there as in the lower grits, but make up a large part of the rocks, 

 and, weathering out in a purplish tint upon a greenish ground, give 

 a very curious aspect to the surface. What we see here, indeed, is 

 not drifted material brought from a distance to be deposited along 

 with its organic remains, but the actual spot on which colonies 

 of fucoids and sponges luxuriated, and on which they left their 

 remains, their most constant Molluscan companion being the great 

 Lima pectiniformis. 



The beds thus described are very variable in character and thick- 

 ness ; and the limits between two beds can scarcely be traced for 

 more than a few yards. We have found in them the following 

 fossils : — 



Ammonites achilles (B' Orb.). 

 Belemnites nitidus (Bollf.). 

 Pleurotomaria Mlinsteri {Rom.). 

 Littorina pulcberrima (Bollf.). 

 Astarte o^ata (Sow.). 



supracorallina (B'Orb.). 



polyrnorpha (Cont.). 



Pholadomya hemicardia (Ag.). 

 Pleuromya tellina (Ag.). 

 Gresslya peregrina (Ph.). 

 Thracia depressa (Sow.). 

 Goniomya literata (Sow.). 

 Cardium delibatum (Be Lor.). 

 Lucina substriata (Rom.). 

 Trigonia muricata (Goldf). 

 Pinna pesolina (Cont.). 

 Pecten midas (1)' Orb.). 



Pecten distriatus (Leym.). 

 Lima pectiniformis (Sow.). 



rigida, (Sow.). 



Hinnites velatus (Goldf.). 

 Avicula sedilignensis (Blake). 

 Plicatula, sp. 

 Exogyra nana (Sow.). 

 Ostrea deltoidea (Sow.). 



solitaria (Sow.). 



duriuscula (Ph.). 



Serpula tetragona (Sow.). 



sulcata (Sow.). 



Discina Humphriesiana (Sow.). 

 Lingula ovalis (Sow.). 

 Cidaris florigemma (Ph.). 



Smithii ( Wr.). 



Echinobrissus scutatus (Lam.). 



The rocks which we are now describing make a very marked 

 feature on Linton Hill, where they score the hillside with a ruddy 

 sloping cliff, to the east of that which is composed of the Trigonia- 

 beds (see fig. 1, c). The characters are here very similar to those 

 at Sandsfoot, the lower and more ferruginous beds being alone 

 exposed. We see the same variegated concretions and branching 

 organisms, and meet with the same fossils, though more sparingly. 

 They are also exhibited in considerable thickness in the Fleet, 

 their maximum lying perhaps rather south and west. 



In the neighbourhood of Osmington and in the western part of 

 Ringstead Bay, this series is also well developed, the divisions 

 being nearly the same as at Sandsfoot, though the beds are, as 

 a whole, more argillaceous. Thus on this side of Weymouth 

 Bay the " Sandsfoot Grits " are largely mixed with clayey matter, 

 and therefore make less show on the cliff. Yet it is quite possible 

 to identify them both west of Osmington and in Ringstead Bay 



