402 Proceedings of the TTernerian Society. 



From what source the dark substance forming the scum on Loch Voil 

 was derived, it were difficult to say. Dr Traill mentioned, that, in 

 Orkney, about 178'2, a dark powder fell from the atmosphere, which 

 was at the time generally ascribed (and probably correctly) to Hecla, 

 which was then in eruption. At the same meeting was read a notice 

 of two remarkable animals from the Firth of Forth, communicated by 

 Edward Forbes, Esq. In July 1839, Mr Forbes observed among crowds 

 of Medusae and Cydippes, congregated around the shores of the Isle of 

 May, two minute animals in considerable numbers, and .presenting 

 such anomalous characters (especially one of them) that their position 

 in the animal series became a matter of question. The first of these 

 animals, Mr Forbes at last referred to a new genus of molluscs, de- 

 scribed and figured in the voyage of the Astrolabe, under the name of 

 Briarea. This genus, however, is believed to be prOperly crustaceous 

 not molluscous. The new species was called B. truncata. The other 

 animal was so anomalous that no attempt was made to refer it to any 

 known family in the animal kingdom ; but as it is by no means rare, 

 future investigation may clear up the difficulty. 



April S. — Professor Jameson, President, in the Chair. 



Dr Robert Hamilton read a paper, entitled, Sketch of the Geology 

 of the Basin formed by the rivers Euphrates and Tigris. The author 

 remarked, that, as suggested by Mr Ainsworth, this interesting region, 

 including ancient Assyria, Mesopotamia, and Chaldea, may naturally 

 be divided into three distinct districts ; the 1st, of plutonic and meta- 

 morphic rocks; the 2d, of sedimentary formations; and the 3d, of alluvial 

 deposits. The first of these is marked by three somewhat parallel 

 mountain ranges, stretching in an east and westerly direction, namely, 

 the Niphates, the Agavah Dag, and ^the ancient Masius. The central 

 nucleus of these vast chains consists of granite, gneiss, and mica-slate, 

 with limestones, greenstones, and hornblende. The most northerly 

 range is probably the highest of the Taurus, towering above the line of 

 perpetual snow, which may be estimated at about 10,000 feet. The 

 more particular survey commenced in the central range, near the junc- 

 tion of the eastern and western branches of the Euphrates, at the town 

 of Kebban, where silver and lead mines are worked, which yield an- 

 nually about 1000 pounds of the former metal, and 195,000 of the 

 latter. An account was next given of the geology of the country in the 

 neighbourhood of the copper mines of Arghana, which was said to pro- 

 duce annually 2,250,000 pounds of this metal. The second district 

 was described as extending from 37° N. lat. to 34°, and laterally 



