66 



be taken as the most complete section of this division, the Upper 

 Freestone is 34 feet, the Oolite Marl 7 feet, the Lower Freestone 

 147 feet, the Pea-grit and Ferruginous Eagstone 40 feet in 

 thickness; the latter resting on the Cephalopoda bed and sands 

 of the Upper Lias. 



The upper portion of this zone is weU exposed in the North 

 Quarry, half a mile distant from the Rolling-bank. The sandy 

 subsoil feels boggy to the tread, and is thrown up into 

 numerous elevations by the burrowing of rabbits. There is a 

 gap in my section between the base of the Oyster-bed 'No. 6 and 

 the next stratum No. 7, which I have not been able to fiU up, 

 as in none of the exposures do we find the consecutive beds in 

 super-position. The missing stratum may be represented by the 

 Marly OoHte found beneath the Oyster-bed in the RoUing-bank 

 Quarry; but of this I have no evidence. 



No. 5. — The Road-stone consists of a coarse, brown, ferruginous, 

 OoHtic Limestone, hard and crystalline in some parts, and in 

 others traversed by sandy layers, containing concretionary 

 masses of calcareo-siliceous rock, having an unequal fracture, 

 and crystaUine structure. It contains a small assemblage of 

 Mollusca, many of which are specifically distinct from those of 

 the upper beds, as Chemmtzia Scemanni, Oppel., nearly identical 

 with the Coralline OoKte species, C. striata, Sow., gigantic forms 

 of Pholadomya Heraulti, Ag., and very large shells of Trichites 

 undnilatus, Lye. This bed varies in thickness from ten to fifteen 

 feet. 



Cephalopoda. 



Ammonites Orbignianus, Wright. Ammonites Brocchi, Sow. 



Humphriesianus, Sow. —. Braikenridgii, Sow. 



Sowerbii, Mill. Nautilus lineatus, Sow. 



Gasteropoda. 



Chemnitzia Scemanni, Oppel, Pleurotomaria fasciata, Sow. 



• lineata, Sow. elongata, Sow. 



Turbo laevigata, Sow. constricta, Deslong. 



