700 XRANSACTIOMS Of SECTION C. 



))reccialed limestone about 1,000 feet from the base. About 2,600 feet 

 thick (top not seen). Diplograijhts dcntatus, PhijUograptus, Didipno- 

 graptus extensus, and D.fasciculatus^. 

 {h) Doolougb Slates, on north side of Killary Harbour. Green slates, with 

 subordinate grit bands, with Diployraptus dentatus, Phyllograptus 

 (four species) and other forms, including a N. American species of 

 Glossograptiis and a new form, G. accmthus. E. it W. MS. 



.3, Mireelrea Grits (Llandeilo and (?) Bala). — Current-bedded red and greyish- 

 green, felspathic grits, resting conformably on the Doolougb Slates. Apparently 

 12,000 feet thich (top not seen). Green shale bands in lowest 3,000 feet, with 

 Q'/y.'/'f f "d brachiopods. Uppermost 9,000 feet barren. 



4. Oirenduff Beds (Upper Llandovery and Wenlock). — Basal breccia, with 

 fragments of schist, rests uncoiiformably on theConnemara Crystalline Schists and 

 is succeeded by red mud-stones, barren green grits, calcareous grits with 

 brachiopods, a coarse conglomerate containing quartzite boulders, and a thick series 

 of grey v.-acke grits and green sandy shales, in all about 5,300 feet thick. About 

 !i,300 feet from the top is a band containing Motiograptitg Riccartonensis, and 

 about 300 feet from the top another containing Monograptus vomerinus and other 

 fossils. 



.O. Salroch Slates (Ludlow). — A monotonous series of dull Indian red and 

 pale green slates overlying Owenduft" Beds conformably. A few bands contain 

 Lingida Davisi, L. Symondsi, &c. About 3,000 feet tliiclc (top not seen). 



The strata are arranged in a general east and west syncline through which, 

 along the south side of Killary Harbour, runs the great reversed fault of Salrock 

 Pass, hading to the north, and bringing- up Arenig rocks on to Ludlow and 

 AVenlock beds. 



All the rocks are more or less cleaved, but the folding is on the whole quite 

 gentle, although in the northern part of the district the Doolougb Slates show 

 considerable compression and packing from the north against the great mass of 

 the Mwcelrea Grits, and at the same time an appreciable development of seri- 

 ciiic mica. 



The Arenig conglomerates contain boulders of quartzose schist identical with 

 some of the Counemara Crystalline Schists. Hence the latter were metamorphosed 

 before Arenig times, and are prebumably of Archrean age. 



f). Notes on the Petrography of Egypt. By W. F. Hume, D.Sc. 



1. The ancient core of the North-east African continent consists of the 

 Cataract and Sudan Banded Gneisses, which may represent a very ancient 

 igneous magma. They are usually much veined by granitic dykes. 



2. In certain places in the Arabian Desert, Cataracts, &c., these underlie highly 

 metamorphosed Schists (the Mica-Schists of Sikait, the Calcareous Schists of Um 

 Garaiart and Haimar and of the Amara Cataracts, also the Dolomites of the 

 latter region), which are sharply separated from the Banded Gneisses, and are 

 possibly the oldest sedimentary representatives in Egypt. 



3. The greater part of the mountainous regions of the Eastern De.sert and 

 Sinai are occupied by two types of rock, a schistose constituent overlying or being 

 surrounded by the acid member (o) the first-named, the Dokhan Volcanic Rocks 

 and Schists, are partly volcanic in origin and partly sedimentary, the former being 

 represented by lavas of various types, while the latter are clearly altered sedi- 

 mentary strata (grits, conglomerates, &c.). No fossils have yet been found, but 

 they have their nearest analogues in the latest pre-Cambrian and Cambrian series. 

 Here are included some of the most interesting rocks of Egypt, such as the Imperial 

 Porphyry and the Breccia Verde Antico. 



(6) The igneous member intruded into these ancient sediments, &c., includes 



