136 ■ Reports and Proceedings — 



The essential minerals are arranged in the following order, based on 

 their general distribution in the different tj'pe of rock : — Olivine, 

 pyroxene, hornblende, biotite, plagioclase, orthoclase and quartz, 

 microcline. The following is the order in which the principal con- 

 stituents commence to form in the rocks : — Iron-ores, olivine, 

 P3'roxene, hornblende, biotite, plagioclase, orthoclase, microcline, 

 and quartz. The chemical composition of the roclvs is discussed, 

 data being furnished by a series of analyses made by Mr. J. H. 

 Player, and a diagrammatic representation of the molecular relations 

 of the different bases and silica is given. The relations between 

 mineralogical composition, chemical composition, and geological age 

 are then considered ; and the following conclusions are reached : — 



(1) That the various rocks have resulted from the differentia- 

 tion of the originally homogeneous magma. 



(2) That the chronological sequence from peridotite to eurite 

 is connected with the order of formation of minerals in 

 igneous magmas. 



3. "North Italian Bryozoa. — Part II. Cyclostomata." By Arthur 

 William Waters, Esq., F.G.S. 



The Chilostomata from the same localities were dealt with in 

 volume xlvii. of the " Quarterly Journal." In the present paper a 

 number of Cyclostomata are described, amongst the most interesting 

 being a new species termed by the author Diastopora brendolensis, 

 which has tubules similar to those of D. ohelia. These are the only 

 species in which tubules are known, and two modes of growth of the 

 fossil seem to show that those who united under Diastopora erect 

 and incrusting forms were right. 



The ovicell by the side of the zoarium of Hornera serrata, described 

 in the paper, is in a position new for the Cyclostomata. 



II.— Feb. 10, 1892.— Sir Archibald Geikie, D.Sc, LL.D., F.K.S., 

 President, in the Chair. — The following communications were read : 



1, "The Raised Beaches, and 'Head' or Rubble Drift of the 

 South of England: their relation to the Valley Drifts and to the 

 Glacial Period ; and on a late Post- Glacial Submergence. — Part I." 

 By Joseph Prestwich, D.C.L., F.R.S., F.G.S. 



The author remarks that, besides the subaerial, fluviatile, and 

 marine Drifts of the South of England, there is another Drift which 

 is yet unplaced. This he considers to be connected with the 'Head' 

 overlying the Raised Beaches. Of these he describes the distribution, 

 characters, and relations along the South Coast. The ' Head ' over- 

 lies the beaches, and frequently overlaps them. In the beaches large 

 boulders are found, and marine shells, of which lists for the various 

 localities are given. The ' Head ' frequently shows rough stratifica- 

 tion of finer and coarser materials. It contains mammalian bones, 

 land-shells only, and occasionally flint implements. On the coasts 

 of Devon and Cornwall it is separated from the Raised Beaches by 

 old sand-dunes. 



In South Wales the beach occurs below the mammaliferous cave- 



