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J. F. BLAKE AND W. H. HTTDLESTON ON 



Nautilus hexagonus (Soto.). 

 Pleurotomaria MUnsleri (Bom.). 

 Turbo Meriani (Gold/.). 

 Cerithium rauricatum (Sow.), var. 

 Trigonia, sp. (cf. Bronnii, Ag.). 

 Opis Phillipsi (Mor.). 

 Astarte depressa (Gold/.). 

 Lucina circumcisa (Zit. $ G.). 

 Area asmula (Ph.). 



Sowerbya triangularis (PL). 

 Modiola suba?quiplicata (Gold/.). 

 Avicula ovalis (Ph.). 



inrequivalvis (Sow.). 



Lima elliptica (Whit.). 

 Pecten lens (Sow.). 



subtextorius (Gold/.). 



fibrosus (Sow.). 



Exogyra nana (Ph.). 



A very remarkable list, if rightly determined, showing, as it does, 

 several forms unknown elsewhere, the whole pointing to the upper 

 part of the Oxfordian portion of the series. 



3. The Calne District. 



For some miles north of this section at Seend the Corallian series 

 is chiefly represented by beds on the same horizon ; but at West- 

 brook we enter upon the area in which the formation was first 

 studied, and where the names originally applied are indeed ex- 

 tremely appropriate, but which must be considered in reality 

 exceptional with reference to the whole of England, in being gene- 

 rally deficient in the numerous deposits which intervene between 

 the early arenaceous series and the Coral E-ag with Cidaris flori- 

 gemma. So great is the interval thus represented, as indicated to 

 us by the great masses of oolite in the regions already described to 

 the south, and the still more important ones developed in the north, 

 that we are inclined to say of a bed of Coral Eag resting on Lower 

 Calcareous Grit that it may be of any age, especially if it be not 

 covered by any upper arenaceous or ferruginous series. Learning, 

 indeed, from other localities, the enormous lapse of time between the 

 formation of the Lower Calcareous Grit, indicated by its ordinary 

 fossils, and the Kimmeridge clay, we must look upon any small coral 

 growth that rests upon the former as representing but a very small 

 portion of it, the date depending on the occurrence of the physical 

 conditions to which such growths are subject. We cannot speak of 

 the Coral Eag ; for a Coral Eag may be of very various ages. Thus, 

 at Westbrook, we have a fine coral reef, the first in oar journey 

 northwards that we have been able to examine in situ. Layer upon 

 layer of large masses of Thamnastrcea concinna and Isastrcea eccpla- 

 nata, bored by the characteristic Lithodomus inclusus, and changed not 

 seldom into crystalline limestone, in which the organic structure is 

 no longer visible, here spreads over the surface, resting immediately 

 upon a bed of sand, which is itself not far removed in elevation 

 from the Oxford clay. The spaces between the coral growths are 

 filled with a rubbly brash, made up of comminuted materials, and 

 sometimes with clay charged with fragments of shells. These inter- 

 coralline accumulations obtain the mastery here and there ; corals 

 disappear, and we have great rubbly beds of shelly clay and linie- 

 stoie brash forming the whole reef. This is what we might 

 expect, and have often to infer: but it may here be seen and proved. 

 In the intercoralline beds the chief recognizable fossils, which are 



