68 ALBIAN FOSSILS DISCOVERED AT OKEFORD FITZPAINE. 



REMARKS. The matrix surrounding the shells from the Acan- 

 thoceras mammillatum zone "is mostly of an argillaceous sandy 

 character, slightly micaceous, and of a brown, grey, or yellowish 

 colour. That associated more particularly with the specimens of 

 Ostrea and Exoyyra exhibits an oolitic structure, the grains of 

 which are heavily charged with hydrated oxide of iron. This 

 fossiliferous bed, containing also some small siliceous pebbles, has 

 a thickness of five feet, and lies about twenty-eight feet from the 

 surface ; beneath is a deposit of pure sand, having a depth of three 

 feet, which reposes on a stiff blue clay of, probably, Kimmeridge 

 age ; at the base of this occurs a sandy rock-formation which possibly 

 belongs to the Corallian period. Immediately above the A. mam- 

 millatum zone is a seam of brown sandy rock, four feet in depth, 

 succeeded by fifteen feet of a grey-coloured sandy clay (of a bluish 

 tint when damp), with phosphatic nodules interspersed (a section 

 of one showing veins of calcite) ; both these bear a Lower Gault 

 fauna, characterized by Hoplites interruptus, &c. Then follow two 

 unfossiliferous bands one of brown clay, five feet thick, the other 

 of yellow clay with angular fragments of chert, three feet thick ; 

 a foot of subsoil occurring above this completes the section." 



DESCRIPTIONS OF THE FOSSILS. 



(A) THE ACANTHOCERAS MAMMILLATUM ZONE. 



Acanthoceras mammillatum, Schlotheim sp, 

 Hoplites Benettianus, J. de C. Sowerby, sp. 

 Pleuromya plicata, J. de C. Sowerby, sp. 

 Cucullcea carinata, J. Sowerby, sp. 

 Ostrea Leymeriei (Deshayes MS), Leymerie. 

 Exogyra sinuata, J. Sowerby. 



MOLLUSGA Cephalopoda. 

 ACANTHOCERAS MAMMILLATUM, Schlotheim. 



Plate 1, fig. 1-2. 



Ammoniten, Walch : Der Naturforscher 1774, Vol. I., PI. 2, 

 fig. 3, p. 196. 



