48 report — 1865. 



not been met with in other beds than the Stinking Coal, and in the stony 

 8-foot ironstone at Kidsgrove. Pcecilodus is a common form in the Cockshead 

 ironstone shales, and has a tolerably wide range from the Stinking Coal 

 upwards. The little tooth with numerous cusps is confined to the New and 

 Deep Mine ironstones, but is frequent in the former bed. In addition to 

 these, there is a fine lancet-shaped tooth rarely found in the Deep Mine, 

 Wood's Mine, New, Bassey Mine, and Gubbin ironstones, to which at present 

 no name has been assigned. 



The Mollusca of these fields may be divided into three distinct groups — • 

 the Avieulopecten and Goniatite group of the lowest measures, the Spirifer- 

 and Distinct group of the middle, and the Anthracosia of the entire fields. 

 The Avieulopecten of the lowest measures is represented simply by the species 

 papyraceus, and is confined to two horizons, that of the Stinking Coal about 

 100 feet above the Millstone-grit, and a lean grey ironstone about the same 

 distance above the Stinking Coal. In the latter bed it is associated with 

 Goniatites, Posidonia, Orthoceras, and Lingula, each of which are invariably 

 found to occupy different and successive levels in the deposits to which they 

 are confined. 



Immediately upon the coal, which is strongly sulphureous, comes a bed 

 of Aviculopectens, from 6 to 8 inches thick ; this is succeeded by a layer of 

 Goniatites of similar thickness ; then Posidonia and Orthoceras ; the black 

 shales containing fish, and at the top of all comes Lingula mixed with 

 scales of Ptdceoniscus. The Avieulopecten, Goniatites, Posidonia, and Ortho- 

 ceras bands are generally dovetailed, as it were, into each other, but each 

 contains nevertheless its characteristic features. Lingula is, however, always 

 sharply cut off from them and confined to one definite line on the top of the 

 shales immediately below the bone-bed which separates these fossils from the 

 on-coming C'gtheropsis and Anthracosia. The Aviculopecten-bed is of great 

 areal extent, and retains a remarkable degree of uniformity in whatever 

 district it is found, and in more than one important case the existence of 

 certain valuable mineral deposits have been determined by its presence alone. 

 In the Goldsitch-moss basin, 10 miles direct north from Ipstones, it forms 

 one of the coals worked there under the name of the Thin Seam ; at Wetlcy 

 Moor it is represented by the Four-foot coal, at Biddulph by the Biddulph 

 Moor coal, and in each locality it contains its characteristic tranquilly 

 deposited fossils, in equal numbers and corresponding conditions. 



The other Aviculopecten-hed is a thin grey laminated ironstone about 100 

 feet above the Stinking Coal, and hitherto has not been detected beyond the 

 limits of the Churnet valley. Its fossils are in a fine state of preservation, 

 but so far it has not been found to contain other remains than Avieulopecten 

 papyraceus and Posidonia. 



The base of the lowest measures of the Churnet valley is a clayey marl, 

 which reposes directly upon the upper beds of the Millstone-grit, and varies 

 in thickness from a thin film to 15 feet. This is succeeded by the well- 

 known Hydrate, a most curious and remarkable deposit, varying from an 

 inch to 2 feet 6 inches. The shales in contact with this ore, and the stone 

 itself in certain localities, contain great numbers of Anthracosia acuta — a form 

 of life which take3 precedence of all others in the history of the period 

 represented by these rocks. Between this bed and the Stinking Coal the 

 only recognizable fossils are scanty remains of fishes ; but here, as before 

 stated, Anthracosia again comes in, and again gives place to the Avieulo- 

 pecten of the laminated ironstone. In the succeeding clay ironstone nodules 

 it is accompanied by other species, but from this point up to the marine bed 



