114 BRITISH CRETACEOUS BRACHIOPODA. 



is required : but viewing all the beds as one whole, we recognise therein from 

 twenty-eight to thirty species, or the maximum of specific and numerical development of 

 the Brachiopoda in the Cretaceous system in Great Britain. 



In the Isle of Wight two well-separated beds may be traced above the Gault. First, the 

 Upper Green Sand, from which Mr. S. H. Saxby procured Lingula sub-ovalis (Dav.), a 

 Terebratula, probably T. squamosa (Mantell), Ter. biplicata, var. (Sow.), Eh. nuciformis 

 (Sow.), and E. depressa (Sow.). The second bed is termed the Chloritic Marl, and 

 from which the same gentleman obtained Ter. biplicata (Brocchi), T. pectita (Sow.), Eh. 

 Grasiana (D'Orb.), E. compressa (Lamarck), and E. Mantelliana (Sow.). The fossils 

 from both being identically similar to those so abundantly found in the neighbourhood of 

 Warminster. 1 



One of the most interesting localities in England for the study of the beds under 

 notice is the neighbourhood of Chard and Chardstock, and I am particularly indebted to 

 Mr. J. Wiest for the following details. 



" The formations about to be described are situated chiefly, if not exclusively, on each 

 side of the valley of the Kit, and consist of the following beds taken in the descending 

 order:" 



I. Lower Chalk without flints, from two to thirty feet in thickness at different places ; 

 its fossils are those common to that deposit and age. 

 II. Chalk Marl or Discoidean stratum, from two to three feet in thickness, representing 

 a homogeneous mass, with fine siliceous and chloritic grains ; it spreads out 

 more equally than No. I, but does not appear to be present where the last 

 attains a considerable thickness. Am. Mantelli, Discoidea cylindrica, and 

 Ananchites subglobosa, are amongst its fossils. 



III. The Scaphites bed, harder than I and II., and, before becoming exposed to air and 



damp, a compact accumulation of fossils, from three to nine inches in thickness ; 

 siliceous grains, more numerous and rough than in II, are interspersed in the 

 mass. Scaphytes, Nautilus triangularis, M.ontfort,=Fleuriausianus, N. lavigatus, 

 Am. varians, A. obtectus, and Galerites, are amongst its fossils. 



IV. Green bed, near Chardstock, distinctly separated from III, forms a hard compact 



mass of rocks, with abundant siliceous and chloritic grains ; from six inches to 

 three feet in thickness, and containing the greatest variety of fine fossils. 

 Nucleolites Morrisii, N. lacunosus, Ter. lyra, and other Upper Green Sand fossils 

 characterise that deposit. 

 V. Crustacean stratum, less cemented than IV, with siliceous grains predominant; 

 one to three feet in thickness. It contains a few Terebratula, Pectens, but 

 chiefly remains of Crabs. 



[ Consult also the valuable ' Memoirs on the Geology of the Isle of Wight,' &c, by Dr. Fitton, 

 Professor Forbes, and others, published in the * Transactions and Quarterly Journal of the Geol. Soc. of 

 London.' 



