In considering the mutual relations of the sciences of Geology and Chemistry, the student must always bear in mind which of these two sciences is to form the basis or starting point for his inquiry, for this cannot fail to exercise an important influence on his reasonings and deductions.

The geology of Charnwood Forest appears to have been first systematically investigated by Professors Sedgwick, Whewell, and Airy in 1833. A very brief notice of their labours by C. Allsop, Esq., is appended to the history of Charnwood Forest by J. R. Potter, 1842, as is also a valuable and detailed memoir on the geology of the district, by J. B. Jukes, Esq.

The importance of the question of conformity in the classification of the earliest stratified rocks induces me to give a short description of a new section of a part of the Cambrian rocks of Llanberis, exhibiting an apparent case of unconformity towards their base.

Gen. I. Rastrites, Barr. (Grapt. de Boh. p. 64). Polypary simple, consisting of a slender capillary common tube, supporting a single series of isolated hydrothecæ, which are free throughout their whole length.

The fossil about to be described was obligingly sent to me by Dr. Bull, of Hereford, having been happily rescued from the remorseless hammer of the road-mender, by Richard Johnson, Esq., the Town Clerk of that city. It exhibits the shell in section, fractured longitudinally, and embedded in a hard compact mass of dark blue Woolhope Limestone, which may be seen well exposed in situ in the Little Hope quarries, near Woolhope, from whence the block which contains the fossil was derived. Dr. Bull informs me that the Woolhope Limestone from these quarries is always used for road-metal in the surrounding district.