ZONE OF AMMONITES JURENSIS. 91 



The Cephalopoda Bed — Upper Lias. 



Zone of Ammonites Juiiensis. 



Ft. ill. 



d. A coarse, dark-brown, calcareo-siliceous rock, full of small, dark, flattened grains of 

 hydrate of iron. It contains an immense quantity of fossils, but Ammonites and 

 Belemnites are the dominant forms ; some of the bivalve shells are well preserved ; 

 the matrix adheres to the surface with such tenacity that they can seldom be cleaned 

 without injury. The Ammonites and Nautili, for the most part, want the shell. 

 Bhi/nchonella cijnocephala lies in the upper part of the bed, and the Ammonites, 

 Belemnites, Nautili, and other Mollusca in the middle part ; the lower part is not so 

 fossiliferous ; this bed measures I 6 



€. A hard, coarse, brown mudstone, with hard irregular nodules of a calcareo-siliceous 



sandstone, highly micaceous and ferruginous, and passing downwards into the sands . 9 



/. Fine, brown and yellowish, micaceous sands, passing into grayish coloured micaceous 

 sands, with inconstant and concretionary bands of highly calcareous sandstone ; 

 nodules of various size occur in these bands, which are sometimes fossiliferous, con- 

 taining chiefly Ammonites and Belemnites loO .' 



Zone of Ammonites communis. 



g. Blue clay and shale, marked by the outburst of springs and by pools of water on the 



terrace formed by the Upper Lias Clay 80 



Zone of Ammonites makgaritatus. 



h. Marlstone ; a hard calcareous sandstone, resting on brown and gray sands, with bands 



and nodules of ferruginous sandstone 1.50 



Zone of Ammonites capricornus. 

 i. The shales of the Middle and Lower Lias, sloping down into the valley, 



Fossils of the Inferior Oolite. 



A. Very few fossils in the Freestone ; those observed were mostly fragmentary. 



B. The fossils in this bed are so much broken that I have not been able to determine them. 



Stems and column-plates of Extracrinus, portions of the tests of Pygaster semi- 

 sulcatus, Phil., and Acrosalenia Lycetti, Wr., plates of Cidaris, and quantities of 

 spines in fragments, are seen on the slabs. 

 c. The following shells were observed, but could not be extracted from the upper part of the 

 bed: 



Pholadomya fidicula, Sow. Trichites nodosus, Lye. 



Modiola plicata, Sow. Serpula socialis. Gold/. 



The frond of a Fern was found in this bed by the Rev. P. B, Brodie. The lower part 

 of the rock resting on the Cephalopoda bed is sparingly fossiliferous. 



In very few localities, where the sands are exposed along the escarpments of the 

 Cotteswolds or in the beautiful valleys intersecting these hills, are they found to contain 



