234 Reports and Proceedings — 



numerous other points of resemblance in these skeletons noted 

 b}' Baur, lead to the conclusion that (he Plesiosauria are descended 

 from a primitive Ehynchocephalian reptile, as already opined b} r 

 Baur, Boulenger, and others. 



2. " On certain Granophyres, modified by the Incorporation of 

 Gabbro Fragments, in Strath (Skye)." By Alfred Harker, Esq., 

 M.A., F.G.S. (Communicated by permission of the Director- 

 General of the Geological Survey.) 



The rocks descrihed form a group of irregular intrusions, the 

 largest less than a mile in length, situated in the tract of volcanic 

 agglomerate north and west of Loch Kilchrist. They differ from 

 the normal granophyres, abundantly developed in the neighboiu-hood, 

 in being darker, denser, and manifestly richer in the iron-bearing 

 minerals, while in places are seen numerous small rock-fragments 

 evidently of extraneous origin. 



The fragments are mainly of gabbro. Closer examination shows 

 that they have been abundantly distributed through the granophyre, 

 but most of them have been more or less completely dissolved. 

 The clearest evidence of this is afforded by the augite of the gabbro, 

 which has been less readily attacked by the magma than the 

 other minerals, and is seen in isolated crystals in various stages of 

 conversion to hornblende. The material dissolved has rendered the 

 acid magma less acid, and has influenced accordingly the products 

 of final consolidation. The granophyre is roughly estimated to 

 have taken up about one-fourth of its mass of gabbro, and this 

 material has been derived, not from the rocks seen in contact with 

 the intrusions, but from some subterranean source. 



3. " Observations on the Geology of the Nile Valley, and on the 

 Evidence of the greater Volume of that Eiver at a former Period." 

 By Prof. E. Hull, M.A., LL.D., F.R.S., F.G.S. 



The author draws attention to the two great periods of erosion of the 

 Nile Valley — the first during the Miocene period, after the elevation 

 of the Libyan region at the close of Eocene times, and the second 

 during a " pluvial " period extending from late Pliocene times into 

 and including the Pleistocene. He notes the course of the river 

 through escarpments of the granitic and schistose rocks of Assuan, 

 the Nubian Sandstone, the Cretaceous limestone, and the Eocene 

 limestone ; and observes that in places the line of erosion of the 

 primeval Nile was directed by dislocations of the strata. Evidence 

 of the unconformity of the Nubian Sandstone upon the granites 

 and schists of Assuan is given, and some observations made upon 

 the age of the different parts of the Nubian Sandstone. 



In the second part of the paper the terraces of the Nile Valley 

 are described, and full details given of the characters of a second 

 terrace, at a height varying from 50 to 100 feet above the lower 

 one, which is flooded at the present day. The second terrace is 

 devoid of vegetation, and its deposits have frequently furnished 

 river-shells such as Cyrena fluminalis, JEilieria semiuidnta, Unio, 

 Paludina, etc. The second terrace is traceable at intervals for 

 a distauce of between 600 and 700 miles above Cairo. Two old 



