The following facts and conclusions have been brought forward in this paper:— 1. That at Dundry Hill the sequence of strata laid down during the Bathonian–Bajocian ages is incomplete, because there is no deposit to represent the time of the niortensis or Humphriesiani hemeræ; in fact, during these hemeræ denudation was in progress at Dundry. 2. That all the strata of the Aalenian and Bajocian ages have been removed from the eastern end of the hill, so that strata of Bathonian date ( Garantianæ hemera) rest non-sequentially upon deposits laid down during the Dumortieriæ hemera. 3. That this removal has been effected by denudation in Bajocian and even post–Bajocian time. 4. That strata equivalent to what are called elsewhere Midford Sands, Upper Lias, and Middle Lias (Marlstone) are present in the hill, the two former attaining a maximum thickness of more than 60 feet, while the Marlstone crops out at many points along the flanks of the range. 5. That the officers of the Geological Survey have apparently confounded the Marlstone Rock (an ironshot oolite of the date of the spinati hemera) with the well-known Ironshot Oolite (of the date of the Sauzei hemera), a bed nearly 100 feet higher up. 6. That in consequence of this mistake they have, round the greater part of the hill, drawn the base of the Inferior Oolite as far below the Marlstone as this base ought to have been drawn if