1. The isolated aggregations of prisms leaning against each other and all sloping towards the centre (like hop-poles stacked in water), noticed by Mr. Scrope at several places in Auvergne, are the remaining or central portions 6f prismatic masses (as in the lower portions of figs. 18 & 19, and shown in Mr. Scrope's fig. 23, Volcanoes , second edit. 94 94 all the other portions of the mass having been removed by denudation, as intimated by that author.