I. I ntroduction . T hat the geology of Lincolnshire has been generally neglected is perhaps easily accounted for when we consider the difficulties of observation in this district, arising from the absence of sea-cliffs, the paucity of good inland sections, either natural or artificial, and the enormous development of the superficial deposits. This neglect, however, is much to be regretted, as a careful study of the strata of this county, besides revealing many phenomena of great intrinsic interest, is calculated to afford much assistance in working out the mutual relations of the remarkably different sections of Yorkshire and the south of England. It is in the hope of contributing Some materials towards the solution of this important geological problem that the present paper has been prepared. The only previous notices of the district described in this essay, which I have been able to discover, are as follows:— A paper* written by Mr. Bogg, in the year 1816,at the suggestion of Dr. Buekland, gives a tolerably correct account of the succession of beds lying to the west of Louth. Unfortunately, however, the author, relying on mineralogical characters only, was betrayed into the mistake of supposing the highly bituminous, slaty, and shaly beds of the Bain valley to be part of the Coal-measures, and, like many others before and since his time, spent considerable sums in boring for beds of coal in Lincolnshire. In 1820 the district was examined by Professor Phillips†, who was then assisting William Smith to complete the Geological Map of