PLATE IV 



FIG. i. Orbiculoidea nitida. Coal Measures, Coalbrookdale. The glossy, 

 largely chitinous, shell is perfectly preserved in an ironstone 

 nodule. 



FIG. 2. Fragment of Pelecypod shell from the Upper Greensand, near 

 Sidmouth, Devon, replaced by chalcedony in the form of 

 Beekite. 



FIG. 3. Dactylioceras commune. Upper Lias, Whitby, Vorks. From a 

 nodule of cement-stone. Complete and uncompressed. 



FIG. 4. Peronoceras annulatuni (a closely similar species)* Upper Lias, 

 Runswick Bay, Yorks. From the shale, flattened and 

 telescoped. 



FIG. 5. Cliona sp. Flint moulds of the crypts perforating the shell of 

 Inoceramus. Upper Chalk, Sussex. 



FIG. 6. Atrypa reticularis. Ludlovv Limestone, West Knowle, Craven 

 Arms, Salop. Internal mould (ventral side), showing muscular 

 and other impressions. 



