Hypogene Rocks. (_Wond._ p. 806.) _Non-fossiliferous._ Metamorphic (_transformed_) or stratified crystalline rocks. _Subdivisions._-- 1. _Mica-schist System._ (_Wond._ p. 843.) Probably sedimentary rocks altered by high temperature. Mica-slate, Quartz-rock, Crystalline limestone, Hornblende schist, &c. 2. _Gneiss System._ Layers of Gneiss, Sienite and Quartz-rock, alternating with Clay-slate, Mica-schist, &c. Plutonic Rocks; unstratified crystalline masses. _Granitic System._ (_Wond._ p. 844.) Granite--a rock composed of mica, quartz, and felspar; Porphyry; Serpentine; Trap. These rocks occur in amorphous or shapeless masses, and in dykes and veins. _Obs._--No fossils have been detected in these rocks: but the intense igneous action which the masses appear to have undergone, may have obliterated all evidence of animal and vegetable structures, should any have been present, as well as the lines of stratification. By the aid of the microscope, we may yet perhaps solve the mystery which shrouds the origin of these rocks, and the student may take up the investigation with the certainty of obtaining much valuable information, even should the search for organic structures prove abortive. It is not, however, improbable that the siliceous frustules of diatomaceæ may have escaped destruction, and remain to reward the researches of some skillful and patient observer. Volcanic Rocks. (_Wond._ p. 815.) The products of subterranean fire or heat, erupted from profound depths through fissures in the Earth's crust, whether in ancient or modern times. _Subdivisions._-- 1. _Trap, Basalt, Toadstone, Volcanic-tuff_; the erupted materials of ancient extinct volcanoes. 2. _Lavas, Scoriæ, Pumice, Ashes_; ejected by modern volcanoes. _Obs._--These igneous products are of all ages, and they traverse alike the hypogene rocks and the older and newer sedimentary deposits. Their characters, and the effects they have produced, are considered in the work to which reference is made. * * * * *