﻿530 DE. WHEELTON HIND ON THE PALEONTOLOGY [Aug. T905, 



258 feet above the Top-Hard Coal; 80 feet below the Furnace 

 Coal. Durham Coalfield : 17 feet 4 inches above the Five-Quarter 

 Coal. Lancashire Coalfield : 2070 feet below the surface at Brad- 

 ford Colliery, above the Bullion Coal. Yorkshire Coalfield : above 

 the Middleton-Mine and Silkstone Coals. Cannock- Chase Coalfield : 

 Fair Oaks Colliery. 



This species also occurs in the Pendleside Series of North 

 Staffordshire. 



Orbiculoidea jtitida (Phillips). (Pi. XXXV, fig. 3.) 



This species is much dwarfed, and rare in the marine band below 

 the Gin-Mine Coal. Mr. John Ward figured a specimen (op. supra 

 cit.) of this species from the Lower Coal-Measures of Cheadle 

 (North Staffordshire). Above the Pennystone Ironstone, Coalbrook- 

 dale, it occurs very well-developed, but in this bed Productus 

 scabriculus and JSpirifer bisulcatus are also very fine. 



Localities. — North -Staffordshire Coalfield: above the Bay 

 Coal ; above the Priorsfield Ironstone ; below the Gin-Mine Coal, 

 Nettlebank ; marine band, Weston Sprink. 



South Staffordshire: Pennystone. Coalbrookdale Coalfield : with 

 the Pennystone and Chance Pennystone Ironstone. Nottingham- 

 shire Coalfield : 524 feet above the Top-Hard Coal. Durham Coal- 

 field : 148 fathoms below the Hutton seam. 



This species also occurs in the Pendleside Series of the River 

 Hodder (Yorkshire), and 500 feet below the Third Grit at 

 Congleton Edge (Cheshire), and as low down as the Redesdale 

 Ironstone, Northumberland. 



Chonetes laguessiana, mutation Q. (PL XXXV, fig. 4.) 



A peculiar mutation of Chonetes occurs in the band below the 

 Gin-Mine Coal. Its distinguishing characters are: — 



1. The transverse form in the adult. 



2. The extended hinge-line, and rolled ear-like projections (an adult 



character). 



3. The comparatively-large area. 



4. The intercalation of ribs. 



5. The tendency to deep, irregular, concentric grooves in the adult. 



This shell is fairly abundant at the horizon mentioned above, 

 and I know this special mutation from the Coal-Measures of one 

 of the Somerset Coalfields. 1 Jukes quotes a small Chonetes from the 

 Pennystone Ironstone of South Staffordshire, on the authority of 

 Edward Forbes. On comparison with the form of Chonetes which 

 occurs 500 feet below the Millstone-Grit Series at Congleton Edge 

 (Cheshire), the Millstone-Grit form is seen to have much finer ribbing 

 and to be less transverse. I have noted the same elongate hinge- 

 line and pointed extremities in specimens of Chonetes from the Lower 

 Limestone Series of Beith (Ayrshire). The fact that in the young 

 state the Coal-Measure form doe3 not exhibit the peculiarities of its 

 adult, indicates that these characters are the result of evolution. 



1 Mr. H. Bolton has discovered a rich marine bed at Ashton-Vale Colliery, 

 near Bristol, 270 feet below Gay's-Vein Coal. 



