84 
The Limestone rock of all which places Mr. Farey con- 
siders as undoubtedly belonging to the Under-coal or 
Mountain Limestone, and the same perhaps as that of 
Ashford, Bakewell, &c.in Derbyshire High-peak Hundred, 
wherein large Orthocere of several species are found, 
see W. Martin’s “ Petrificata Derbiensia,” tab. 38 & 39. 
Orthoceratites have been considered as characteristic of 
Werner’s Transition Limestone, but in England at least 
they are to be found more frequently in the mountain 
Limestone, and those Limestones or Shales which ac- 
company the lowest seams of Coal. In the oldest Tran- 
sition Rocks of Great Britain it does not appear that they 
have ever been found. 
Very large Orthocere are said by some authors to 
have been met with, but those who have taken the pains 
to give the measures of what they found, have not de- 
scribed any above a quarter of the size of our O. 
gigantea; hence I conceive it must be new. 
The stone this is found in differs from the metalliferous 
or mountain Limestone of England in color, being of a 
deep red, and in having a micacious shale dispersed 
through it. It contains many of the same shells and 
corals ; but this and the following species of Orthocere 
seem peculiar to it. 
