124 THE OLD RED SANDSTONE. 
found that the two collections, though furnished by localities 
more than a hundred miles apart, were yet derived, if I may 
so express myself, from the same low platform, both alike 
representing the fossiliferous base of the system, and both 
removed but by a single stage from the great unfossiliferous 
conglomerate below. ‘Thus there seem to be what may be 
termed two stories of being in this lower formation — stories 
in which the groups, though generically identical, are specifi- 
cally dissimilar.* 
* Since this period, however, several species identical with those 
of Cromarty have been found in the Morayshire deposits. 
