Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne 1838 Vol.2.djvu/156

146 towards the north. Their appearance on this side of the Tees is partly owing to the shelter afforded by the Cleveland hills, but more especially by the warm and fertile soil originating from the decomposition of the Red Sandstone rocks, prevalent in the lower part of this vale.

On referring to the latter pages of this Catalogue, it will readily be seen how greatly its numbers have been increased by the assiduity of Dr. G. Johnston, author of the Berwick Flora, who has shown how much may be learned respecting the most minute cryptogamic productions, by a diligent use of the microscope, and by a fixed determination to follow up a peculiar line of study and investigation.

To my other numerous friends, who have favoured me with specimens or delineations of plants, I beg leave to acknowledge the kindness conferred, and whenever the name of a correspondent is attached to a locality, thanks for the communication are to be implied as a matter of course.