_Purley Park, near Atherstone._--The rock here contains, in addition to the usual brown hornblende, many crystals and grains of clear yellowish augite, and several pseudomorphs after olivine. The augite crystals exhibit the usual forms, some being twins. The pseudomorphs after olivine are quite similar to others observed in certain highly altered dolerites, they consist of calcite or calcite and viridite; they are numerous, and are generally larger than the crystals of augite or hornblende. _Quarry close to Atherstone._--This rock also contains both augite and hornblende; and lastly, in the railway cutting at Chilvers Coton, several interesting varieties of diorite may be found. THE RHYOLITES OF THE WREKIN NEAR WELLINGTON, SHROPSHIRE.--In the large quarry in Lawrence Hill, at the north end of the Wrekin, and at Lea Rock on the Shrewsbury Road, are to be found some of the most beautiful varieties of ancient volcanic glassy rocks hitherto discovered in Britain. The rocks in their present condition do not look like glass, owing to a process of devitrification, which they have evidently undergone. There can, however, be no room for doubt as to their original vitreous condition, for they exhibit, under the microscope, certain peculiar perlitic and spherulitic varieties of structure, associated with characteristic forms of microliths, which are found only in the pitchstone and obsidian varieties of volcanic glass. In the quarry in Lawrence Hill, thick beds of volcanic ashes and agglomerates are to be seen dipping towards the north at a high angle, and an examination of this hill and the Wrekin shows that they both consist of a series of stratified ashes alternating with several flows of rhyolite. One of the ash beds contains numerous spheroidal blocks of thoroughly characteristic varieties of glassy rocks; they have not yet been described, but it may here be stated that, in addition to many typical varieties of known rhyolites, there are also included among them some of the rarer glassy kinds described by Zirkel in his Petrography of the 40th Parallel. Beautiful examples of the spherulitic and perlitic varieties may be found at Lea Rock, and have been described by the writer in the Quar. Jour. Geol. Soc. Vol. xxxiii., p. 449. It has been shown by Dr. Callaway, that all these rhyolites are of Pre-Cambrian age; we have here, therefore, the clearest proof that, during very early geological periods volcanic action was of the same kind, and produced the same results, as in more recent times.