Reports and Proceedings — Geological Society of London. 45 



iron on wood ; and (3) on the action of bacteria ou solutions con- 

 taining calcium-sulphate in solution and ferric oxide in the deposit. 

 In the first series carbonate of liine was deposited in spheres; in 

 the second it was found that iron-salts are preservatives, but lime- 

 salts are not ; and in the third, black mud, largely consisting of 

 ferrous sulphide, was produced, while the calcium-sulphate was 

 converted into carbonate. It is considered that these experiments 

 explain the origin of the ' coal-balls.' 



II.— December 4th, 1901.— J. J. H. Teall, Esq., M.A., V.P.R.S., 



President, in the Chair. 



Professor Bonney, in exhibiting a series of specimens of 

 Smaragdite - Euphotide from the Saasthal, remarked that they 

 illustrated its variations in mineral composition ; the pyroxenic 

 constituent being sometimes diallage, sometimes rather acicular 

 hornblende, sometimes glaucophane, but generally smaragdite ; 

 the felspathic constituent passing from a rather changed felspar 

 to the so-called saussurite ; garnets are sometimes common, white 

 mica occasional : these different kinds pass one into another. The 

 rock also varies greatly in coarseness, and often exhibits a distinctly 

 streaky structure. He described the locality where the rock occurs 

 in situ. 



Dr. Vaughan Cornish, in exhibiting photographs of ' Snow 

 Mushrooms ' taken by him in January, 1901, at Glacier House, 

 near the summit of the Canadian Pacific Railway in the Selkirk 

 Mountains, west of the Eockies (British Columbia), altitude 4,000 

 feet, said that the snowfall had been 25 feet measured, then 

 represented by a 5-foot layer upon the ground. It is said that 

 there is not much wind here, and that the snow mostly falls 

 at a temperature near the melting-point. It has the reniform 

 habit in great perfection, and its clinging masses are very 

 beautiful. The most remarkable thing about it is the formation 

 of symmetrical caps, which overhang, by a yard and more, the 

 supporting pedestal. The stumps of the felled trees usually have 

 bases 2 to 4 feet in diameter, which support the whole depth of snow 

 and are frequently of such a height as to produce, with the cap of 

 snow, an almost perfect reproduction of a mushroom. Their almost 

 perfect symmetry was attained, he believed, by gradual growth until 

 the limit of cohesion was reached in all directions. The tree-stumps 

 being almost exactly circular, the complete cap is also circular. 

 These caps are very stable, the great weight of superincumbent snow 

 welding the lower layers into a tenacious mass. Their study has, 

 at least, a suggestive value to geologists. 



The following communications were read : — 



1. " On a new Genus belonging to the Leperditiad^e, from the 

 Cambrian Shales of Malvern." By Professor Theodore Thomas 

 Groom, M.A., D.Sc, F.G.S. 



Forms referred to Beyrichia have long been known from the 

 Cambrian beds of Scandinavia, Stockingford, and South Wales; and 



