A broad area, lying between the Hollybush sandstone and the unconformably overlying Silurian rocks of Buildwas, is occupied by a series of Upper Cambrian rocks, denominated by Dr. Callaway the Shineton Shales, and characterised by the forms:--_Olenus Salteri_, _Sphæropthalmus_, _Asaphellus Homfrayi_, _&c._, _Bryograptus Callavei_, _&c._, allying them with the Tremadoc Beds of North Wales. SILURIAN ROCKS. The rocks of the Silurian System are fully developed within the limits of the Birmingham District, under their most typical aspect. The well known localities of Dudley and Barr have been famous in the geological world since the publication of Murchison’s great work, the Silurian System; and the abundance and beauty of the fossils of the limestone rocks of the district place it next to the typical area of Central Shropshire as the representative country of the Silurian rocks. The Silurian strata are all of the well-known Salopian type, shewing several thick-bedded limestones, occurring on distinct horizons in a great thickness of dark blue or grey nodular shales and mudstones. They make their appearance in sharp anticlinal arches in the South Staffordshire coalfield, and along its faulted margins. Four of these exposures occur along the crest of the Lickey-Dudley anticlinal--at Rubery, Dudley Castle Hill, the Wren’s Nest, and Sedgley. The largest continuous exposure is that near the town of Walsall, on the eastern margin of the coalfield. All the Silurian formations from the Mayhill Sandstone to the Ludlow (Aymestry) Limestone are recognisable, but the terminal Downton sandstone is lost below the unconformably overlying Carboniferous. None of the localities, however, shew the complete consecutive series, which is made out by piecing together the sections occurring in the several areas. (1.) LOWER LICKEY HILLS.-- (_a._) _Landovery or Mayhill Rocks._--The usual red and grey _Pentamerus_ sandstone of the Mayhill formation is exposed along the north-west flank of the Lower Lickey Hills. It may be seen resting unconformably upon the Cambrian quartzite in the village of Rubery, and at Leach Heath. Casts of fossils are abundant in some of the sandstones a few feet above the base of the formation, and include the well known forms:--_Pentamerus oblongus_, _Pentamerus lens_, _Strophomena expansa_, _Attrypa reticularis_, _etc._--These may be collected from the rocks at the village of Rubery, and from the fragments of sandstone scattered over the fields between the Asylum and Leach Heath. (_b._) _Woolhope or Barr Limestone._--The Llandovery sandstone is followed (in a stream section below the Asylum) by pale blue shales and mudstones containing a bed of hard calcareous rock, affording examples of _Illenus Barriensis_, _Atrypa reticularis_, _Encrinurus punctatus_, _Rhynchonella Lewisii_; but the section is a poor one, and is covered up almost immediately by the overlying Carboniferous.