entire mass of the limestone. Coll. of T. S., J. H., D. J. B., A. S. Productus longispinus, Sow., Dav. Carb. Mon. Pl. xxxv. figs. 5-19. Upper Limestone series, Cockenzie, Linlithgow, Penicuick, Kirkcaldy; Lower Limestone series, Cousland, Gilmerton, Crighton, Longniddry, Aberlady, Bathgate, Charleston, Kirkcaldy. Very common. Coll. of T. S., J. H., D. J. B. A. S. Productus mesolobus, Phill., Dav. Carb. Mon. Pl. xxxi. figs. 6-9. Productus scabriculus, Mart., Dav. Carb. Mon. Pl. xlii. figs. 5-8. Productus semireticulatus, Mart., Dav. Carb. Mon. Pl xliii. figs. 1-5. Upper Limestone series, Joppa, Prestonpans, Penicuick, Kirkcaldy; Lower Limestone series, Middleton, Gilmerton, Cousland, Crighton, Aberlady, Longniddry, Bathgate, Charleston, Kirkcaldy, Bogie quarry, &c., Very common at all the localities mentioned both in the limestones and overlying shales. Coll. of T. S., D. J. B., J. H., A. S. Productus semireticulatus, variety Martini, Sow., Dav. Carb. Mon. Pl. xliii. fig. 6–8. In most of the foregoing localities. Very common. Coll. of D. J. B., J. H., A. S. Productus semireticulatus, variety concinnus Sow., Dav. Carb. Mon. Pl. xliii. figs. 9-10. Lower Carboniferous Limestone series, Charleston, Bathgate, D. J. B., A. S. Productus semireticulatus, variety Scoticus, Sow., Min. Con. Tab. 69, fig. 3. Lower Limestone series, Bathgate, Charleston. Coll. of J. H., A. S. Productus spinulosus, Sow., Dav. Carb. Mon. Pl. xxxiv. figs. 18-19. Lower Limestone series, Bathgate, Charleston. Very rare. Coll. of A. S., D. J. B. Productus undatus, Defiance, Dav. Carb. Mon. Pl. xxxiv. figs. 7-13. Lower Limestone series, Carlops, Charleston, very rare. Coll. of A. S. Productus Youngianus, Dav., Dav. Carb. Mon. Pl. xxxii. figs 21-23. Lower Limestone series, Aberlady, Longniddry, Mayfield, Middleton, Bathgate, Charleston, Kirkcaldy, Bogie quarry. Coll. of D. J. B., A. S. Retzia radialis, Phill., Dav. Carb. Mon. Pl. xvii. figs. 19-21. Lower Limestone shale, Bogie quarry and Charleston; coll. of R. E., jun., A.S.; rather rare. Rhynchonella pleurodon, Phill., Dav. Carb. Mon. Pl. xxiii. figs. 1-12. Lower Limestone series, D'Arcy, Cousland, Catcraig, Longniddry, Bathgate, Kirkcaldy, Charleston. Common. Coll, of J. H., D. J. B., A. S. Rhynchonella pugnus, Mart., Dav. Carb. Mon. Pl. xxii. figs. 1-14. Lower Limestone series, Cousland along with the foregoing species in nodules of limestone contained in a bed of shale below the thick bed of limestone, Charleston. Coll. of D. J. B., A. S. Spirifer Carlukensis, Dav., Dav. Carb. Mon. Pl.xiii. fig. 14. Lower Spirifer glabra, Mart., Dav. Carb Mon. Pl. xi. figs. 1-9. Lower Limestone series, Cousland, Middleton, Charleston. Rather rare. Coll. of J. H., D. J. B., A. S. Spirifer lineata, Mart., Dav. Carb. Mon. Pl. xiii. figs. 1–13. Lower Limestone series, Gilmerton, Cousland, Middleton, Esperston, Mayfield, Longniddry, Aberlady, Bathgate, Charleston, Kirkcaldy, Bogie quarry, &c. Very common. Coll. of J. H., D. J. B., A. S. Spirifer ovulis, Phill., Dav. Carb. Mon. Pl. ix. figs. 20-23. Lower Limestone series, Middleton, Mayfield, Charleston. Rather rare. Coll. of J. H., D. J. B., T. S., A. S. Spirifer pinguis, Sow., Dav. Carb. Mon. Pl. x. figs. 1-12. Lower Limestone series, Mayfield, Charleston. Rare. Coll. of A. S. Spirifer trigonalis, Mart., Dav. Carb. Mon. Pl. v. figs. 25, 29, 33. Upper Limestones series, Cockenzie, Penicuick, Kirkcaldy; Lower Limestone series, Cousland, Middleton, Esperston, Dryden, Gilmerton, Longniddry, Catcraig, Charleston, Bathgate, Kirkcaldy. Very common. Coll. of D. J. B., J. H., A. S. Spirifer trigonalis, variety bisculcata, Sow., Dav. Carb. Mon. Pl. v. figs. 1-19. Lower Limestone series, Cousland, Bathgate, Charleston, Kirkcaldy. Coll. of D. J. B., A. S. Spirifer Urii, Flem., Dav. Carb. Mon. Pl. xii. figs. 13-14. Lower Limestone series, Mayfield, Cousland, Gilmerton, Longniddry, Bathgate, Charleston, Kirkcaldy. Coll. of D. J. B., J. H., A. S. Spiriferina cristata, variety S. octoplicata, Sow., Dav. Carb. Mon. PL vii. figs. 37-47. Lower Limestone series, Aberlady, Longniddry, Bathgate, Charleston. Rather rare. Coll. of D. J. B., A. S. Streptorhynchus crenistria, Phill., Dav. Carb. Mon. PL. xxvi figs. 1-3. Upper Limestone series, Joppa quarry, Penicuick; Lower Limestone series, Gilmerton, Middleton, Bathgate, Charleston. Not common. Coll. of D. J. B., J. H., A. S. Strophomena rhomboidalis, variety analoga, Phill., Dav. Carb. Mon. Pl. xxviii. figs. 1-13. Lower Limestone series, Charleston, Gilmerton, rare; coll. of J. H., D. J. B., A. S. Terebratula hastata, Sow., variety sacculus, Mart., Dav. Carb. Mon. Pl. i. figs. 27-30. Lower Limestone series, Cousland, Middleton, Bathgate, Charleston, Longniddry. Coll. of T. S., D. J. B., J. H., A. S. Terebratula hastata, variety vesicularis, De Kon., Dav. Carb. Mon. Pl. ii. figs. 1-8. Lower Limestone series, Charleston, Bathgate; coll. of D. J. B., A. S. Terebratula hastata, variety Gillingensis, Dav. Carb. Mon. Pl. i. figs. 18-20. Lower Limestone series, Cousland; coll. of D. J. B., A. S. Note.-In the collections of Messrs Brown, Henderson, and Somervail a few forms still remain to be properly determined, which may prove to belong to species not mentioned in the catalogue. 16th December 1875. D. MILNE HOME, Esq., LL.D., President, in the Chair. A "Review of Mr Kinahan's paper on Metamorphism and Vulcanicity, with some Illustrations and Remarks," by Mr G. J. PRIMROSE GRIEVE, Kirkbank, Burntisland, was read at this meeting. In the course of his paper, Mr Grieve remarked: "The most complete study I have made of vulcanicity is among the Coolin Hills of the Isle of Skye; while, to aid me with these, I visited Portsoy, in Banffshire, and the coast between Girvan and Ballantrae, in Ayrshire. Among the Portsoy rocks I found ample illustrations of Mr Kinahan's regional metamorphism, or metapepsis." 11th May 1876. D. MILNE HOME, Esq., LL.D., President, in the Chair. The following Communication was read: On the Glacial Phenomena of Scotland; with special Reference to the recent Works of Dr Croll and Mr James Geikie. ALEXANDER SOMERVAIL. (Abstract.) By At the very outset it might be preferable at once to define the object of the present paper, in order to prevent any misconception as to its aim, or needless discussion that might otherwise arise. Besides minor points it seeks to deal with the nature of the lower drift deposits; to show that the so-called "interglacial periods" have no substantial existence; and that the conditions under which the lower drift deposits have been formed were not of that severe and rigorous kind that has of late been so vigorously advocated. That the objects here indicated are attained and confirmed by the subsequent reasoning, I myself do not profess dogmatically to believe, although for the present they are my stronger convictions. This chapter in the world's geological history, more than any other, is so problematic and perplexing, that even the most careful observers of its puzzling. phenomena are frequently inclined to halt between sometimes more than two opinions. That the superficial accumulations falling under the term glacial drift have been the product of ice in one or other of its forms no geologist will any more doubt than he would call in question the stratified rocks being other than the result of the deposition of sediment in water; but under what precise forms of ice the drift deposits have been formed, and brought together in their present arrangement, is a question only to be gradually answered with patient observation and correct deduction, so varied and complicated are all the phenomena of the drift deposits. Another great question is evolved out of the former: What is the cause or causes that gave rise to conditions so widely different from what we now enjoy, that should have brought about all the rigorous climatic severity of the Glacial period, covering our country with ice in one or other of its forms, and furnishing the agents by which the whole phenomena of the boulder clay and its associated deposits are alone explicable? The answer to this latter question very much depends on what we consider the exact conditions of the Glacial period to have been. Certain conditions might be quite readily explained on geographical grounds which are patent to human experience and observation. Other conditions might only be explainable on astronomical grounds aided by inductive argument. If the geographical theory, which is the more simple and ascertainable, failed to yield a satisfactory explanation, then we would be justified in having recourse to the astronomical for a solution of the problem. The whole subject has of late been discussed under a variety of forms and from numerous points of view, and most extensively so by Mr James Geikie, in his recently published work "The Great Ice Age." So bold and startling are both his assertions and conclusions that it will not be uninteresting very briefly to examine the evidences on which they are based. The terms till and boulder clay, which have been long, and are still, used by geologists as synonyms, have now been separated by Mr Geikie into two distinct systems or formations, the till being described by him as the older, or lower, the boulder clay as the upper, or more recent. Both of these systems or divisions contain intercalated or interstratified deposits of gravel, sand, clay, and occasionally beds of peat, which are regarded by Dr Croll and Mr Geikie as marking interglacial periods. Each of those interglacial periods, of which there were many, occurred at nearly regular intervals, and lasted for some thousands of years, glacial and interglacial conditions alternating. In order to account for all the complicated phenomena of the Glacial period, the accumulation of till and boulder clay, the grooved and polished surfaces on which it rests, and the directions in which the groovings trend, Mr Geikie, no half-hearted ice theorist, calls in the aid of an agent capable for the work, a stupendous mer de glace, a great ice sheet covering up the whole country, and in some parts attaining a thickness of more than 3000 feet. Indeed, so high of late has this ice mania run, that some of the American geologists, with a genius not uncharacteristic, have demanded for the explanation of their phenomena a sheet of ice of not less than 12,000 feet in thickness in some portions of that country. This great mer de glace, covering Scotland, is made, in its descent from the Highland districts, to overflow all the higher hill ranges, such as the Ochils, with as much ease as a stream would overflow a stone in its bed. As this ice sheet reached the coast, it displaced the sea in all its shallower parts to such an extent that the ice from our northern Highlands is described as coalescing with that coming from Scandinavia on what now forms the bed of the present North Sea. Another mighty stream of ice is made to flow from our western seaboard and over-ride the Hebrides, while smaller streams are described as coming from the Welsh and Cambrian mountains, and uniting with |