270 



J. F. BLA.ZE AND W, H. HUDLESTON ON 



Ammonites plicatilis (Sow.). 

 Turbo ? exiguus (Bom.). 

 Littorina pulcherrima (Doll/.). 

 Cerithium septemplicatum (Bom.). 

 Pleurotomaria reticulata (Sow.). 

 Oardium delibatum (Be Lor.). 

 Trigonia clavellata (Sow.). 

 G-oniomya marginata (Ag.). 

 Cucullsea corallina (Damon). 



superba (Cont.). 



Thracia depressa (Sow.). 



Pholadomya sequalis (Sow.). 



bemicardia (Ag.). 



Avicula pteropernoides (Bl. S( H.). 

 Perna mytiloides (Lam.). 

 Pinna pesoliua (Cont.). 

 Pecten lens (Sow.). 



vimineus (Sow.). 



midas^ Orb.). 



Hinnites velatus (Gold/.). 

 Ostrea deltoidea (Sow.). 

 Cidaris Smithii (Wr.). 



In these beds, which have the same character as the great pelo- 

 lithic formation of which the Corallian beds themselves are, as it 

 were, an exceptional development, we have no physical causes to 

 produce a special fauna ; and therefore we may regard them as 

 giving us a fair index of the lapse of time. The aspect, however, 

 of this fauna, is markedly Kimmeridgian, only a few of the fossils 

 being usually found in Corallian beds. Any one finding this clay 

 inland without the association of the other rocks, and noting the 

 commonest of the fossils, would doubtless call it Kimmeridge Clay ; 

 indeed Prof. Sedgwick, in his description of this very section at 

 Weymouth, boldly calls it so. It serves to show how very much of 

 a Kimmeridgian aspect the upper portions of these exhibit, as the 

 lower ones do of an Oxfordian. We may quote this clay as the 

 " Sandsfoot Clay." 



On this clay lies a series of remarkable sands and grits of a fer- 

 ruginous colour, which are extremely well developed at Sandsfoot and 

 on Linton Hill, but cannot be matched elsewhere in England for 

 extent and thickness, and which are extremely fossiliferous. These 

 have been well described in their lithological characters by previous 

 authors ; but, for the completion of our account, we may be excused 

 the repetition. They may be well seen along the shore beneath 

 and on either side of Sandsfoot Castle. Our section commences 

 below what one of us has called the " Kimmeridge passage-beds," 

 and ends above the Sandsfoot clay. 



Section of the Sandsfoot- Castle beds, in descending order : — 



ft. in. 



1. Tb in band of ironstone 1 



2. Blue marly clay, badly stratified, unfossiliferous 15 



3. Glauconitic ferruginous grit, hardest at tbe top, witb an 



open structure, and having impressions of shells 6 



4. Brown and grey spongy calc-grit of backly fracture, with 



numerous interlacing stem-like bars, and hollow tubes of 



clay. Myacites in the natural position 2 2 



5. Blue clay, with a layer of large, almost continuous iron- 



stone doggers passing downwards into the next, and thus 

 becoming more sandy 7 6 



6. Uniform yellow sand, becoming very ferruginous-looking 



and compact below ; becoming also irregular and concre- 

 tionary. The lower part is distinct in some parts as a 

 purplish ironstone with shales. Very fossiliferous 12ft. to 18 



It is to this lowest set of beds, which we may call the " Sandsfoot 

 Grits," that the chief interest attaches ; and they require more 



