Jan. 13, 1888.] 



SCIENTIFIC NEWS. 



43 



Colonies, enclosing an account of recent Discoveries of 

 Gold in the Transvaal." 



The deposits in which gold has been found, locally 

 known as " banket," consist of a quartz-conglomerate 

 forming so-called "reefs," which traverse the veldt 

 parallel to, but at a short distance from, the rocky ridge 

 of Witwatersrand. The "main reef" has been traced 

 for twenty-five or thirty miles, and varies in breadth 

 from 3 feet 6 inches to 15 feet; parallel and branching 

 " reefs " of smaller dimensions have also been found. 

 The yield of gold is said to be very variable in different 

 portions of the " reef," different samples with from 3 oz. 

 to 5 oz. per ton occurring in close proximity. So far as 

 observation has gone (and the deepest workings have 

 only reached a depth of from 70 to 150 feet), the yield of 

 gold has generally increased as the reefs are followed 

 downwards. 



2. " On the Age of the Altered Limestone of Strath, 

 Skye." By Dr. Archibald Geikie, F.R.S. 



The remarkable alteration of the limestone of Strath 

 into a white saccharoid marble, first described by Mac- 

 culloch, has hitherto been regarded as an instance of 

 contact-metamorphism in a rock of Liassic age. The 

 author now offers lithological, stratigraphical, and palason- 

 tological evidence that the altered limestone is not Lias 

 but Lower Silurian. 



In lithological characters the limestone, where not 

 immediately affected by the intrusion of the eruptive 

 rocks, closely resembles the well-known limestones of 

 the west of Sutherland and Rosshire. It is not more 

 altered than Palasozoic limestones usually are. It con- 

 tains abundant black chert concretions and nodules, 

 which project from the weathered surfaces of the rock 

 exactly as they do at Durness. These cherts do not 

 occur in any of the undoubted Lias limestones of the 

 shore-sections. 



The stratigraphy of the altered limestone likewise marks 

 it off from the Lias. There appears to be a lower group 

 of dark limestones full of black cherts, and a higher 

 group of white limestones with little or no chert, which 

 may be compared with the two lower groups of the 

 Durness Limestone. A further point of connection 

 between the rocks of the two localities is the occurrence 

 of white quartzite in association with the limestone at 

 several places in Strath, and of representatives of the 

 well-known " fucoid beds " at Ord, in Sleat. 



Palagontological evidence confirms and completes the 

 proof that the limestone is of Lower Silurian age. The 

 author has obtained from the limestone of Ben Suardal, 

 near Broadford, a number of fossils which are specifically 

 identical with those in the Durness limestone, and so 

 closely resemble them in lithological aspect that the 

 whole might be believed to have come from the same 

 crag. Among the fossils are species of Cyclonema, Mttr- 

 chisonia, Machirea, Orthoccras, and Piloceras. 



3. "On the Discovery of Trilobites in the Upper 

 Green (Cambrian) Slates of the Penrhyn Quarry, 

 Bethesda, near Bangor, North Wales." By Dr. Henry 

 Woodward, F.R.S. 



The absence in Wales of organisms in the Longmynd 

 and Harlech group renders any discovery of fossils in 

 beds of this early horizon of the utmost importance. A 

 portion of a Trilobite {Palceopyge Rainsayi) and Anne- 

 lide burrows had already been found ; but Dr. Hicks, at 

 St. Davids, has added a sponge, 2 Ostracods, 6 Trilobites, 

 2 Lingulelloe, and 2 Thecw [Agnostus, Phitojiia, Para- 

 doxidcs, Conocoryphe Lyelli, C. biifo, and Microdiscus 



sculpltis). Dr. Hicks has pointed out the singular absence 

 of organic remains in the Longmynds both in Shropshire, 

 N. Wales, and Ireland, and has urged the need of 

 further explorations. As if in answer to this, the 

 author has received from Prof. Dobbie an impression 

 and counterpart of a Trilobite from Bethesda, near 

 Bangor, about 3^ in. long and i| in. broad. These 

 specimens were obtained from the Upper Green bed 

 of the quarry, which immediately underlies the grits 

 forming the brow of Bronllwyd and above the Purple 

 Slates. 



4. " On Thecospondylus Daviesi, Seeley, with some 

 Remarks on the Classification of the Dinosauria." By 

 Prof. H. G. Seeley, F.R.S. 



The author described the anterior third of a vertebra 

 front the Wealden, which, was recognised by Mr. Davies 

 as the cervical vertebra of an animal allied to the genus 

 Ccelurus, Marsh. The only European genus hitherto 

 described in which the vertebras are similarly elongated, 

 compressed, and enveloped in a dense external film of 

 bone is that indicated by the saurian, named Thecos- 

 pondylus Horneri, whose vertebras are about 1 1 centi- 

 metres long, whilst the cervical vertebras now under dis- 

 cussion were 9 centimetres long when complete. The 

 specimen has lost the prezygapophyses and cervical 

 ribs. If these were restored they would probably 

 approximate in shape to those of Ccelurus fragilis. 



ROYAL SOCIETY OF EDINBURGH. 

 At the meeting on December 19th, Sir Douglas Mac- 

 lagan, Vice-President, in the chair, the following com- 

 munication was read by Dr. J. Murray on " The Height 

 and Volume of Dry Land, and Depth and Volume of 

 the Ocean": — Only 2 per cent, of the waters of the 

 ocean, the author said, lay between the surface and 

 a depth of 500 fathoms, while 77 per cent, was situ- 

 ated between depths of 500 and 3,000 fathoms. Beyond 

 the latter depth there was only about i per cent, of the 

 bulk of the ocean. The mean height of the land ot 

 the globe was 250 feet above the sea level, and the 

 mean depth of the ocean 12,480 feet. The mean depth 

 of the area beyond 4,000 fathoms was 14,640 feet. The 

 transitional area occupied 24,000,000 square miles, and 

 the abyssmal area was situated fully three miles below 

 the average heights of continents, and occupied 113 miles 

 or square miles, or more than half of the surface of the 

 earth. The deposits in that region were, in most respects, 

 quite similar to those which made up a very large part 

 of the sedimentary formations of the dry land. In the 

 abyssmal area there was a great abundance of animal life, 

 but the forms from various parts of the area were very 

 similar and unlike those of shallower waters, and the 

 deposits unlike any of the sedimentary deposits of the 

 dryland. If the land of the globe were reduced to the 

 sea level by being removed to and filled up in the shal- 

 lower waters of the ocean, its extent would be about 80 

 million square miles, and the rest of the surface of the 

 earth would be covered by an ocean of 113 million square 

 miles. Should the whole of the solid land be reduced to 

 one level under the ocean, the surface of the earth v/ould 

 be covered by an ocean with a uniform depth of about 

 two miles. 



Sir. W. Turner described, by the aid of diagrams, the 

 formation of the pineal gland in the walrus, stating that 

 he had had three opportunities of examining the brain of 

 that animal. It was interesting, he said, to know that 



