i8 9 3. NOTES AND COMMENTS. 257 



that extraneous pebbles occur in the coal-seams and associated 

 shales in many coal-fields both in Europe and America. 



It seems to be proved that the Northern European sea of the 

 Eocene period was separated from that of the Mediterranean area by 

 a land barrier extending across France and Northern Germany. 

 Hence it has been noticed that the fossil marine organisms to the 

 south bear witness to highly favourable conditions for growth, while 

 those in the north seem to have been stunted by the chilling influences 

 of cold currents. This phenomenon is still further exemplified by a 

 recent study of the British Eocene Bryozoa (J. W. Gregory, Trans. 

 Zool. Soc, vol. xiii., pp. 219-279, pis. xxix.-xxxii.), which are numeri- 

 cally small, both in species and individuals, compared with the wealth 

 of forms that inhabited the contemporary seas of the Mediterranean 

 basin. The northern species are also remarkably dwarfed. The land 

 barrier seems to have been destroyed in middle Eocene times, but the 

 conditions were not seriously modified until later. Incidentally, 

 Dr. Gregory remarks that the species of Bryozoa are not so long-lived 

 as some palaeontologists suppose ; he has no faith in the identification 

 of Cretaceous species with any of those of existing seas. 



The " parallel roads " of Glen Roy are still inspiring those who 

 have the opportunity of studying glacial lakes, and Dr. Robert Munro 

 last year kept the much-discussed Scottish phenomenon in mind 

 while visiting Norway. He found a remarkable example of a glacier 

 lake, formed by a branch of the Hardanger-Jokul, near Eidfiord, and 

 has now communicated a valuable detailed account of it to the Royal 

 Society of Edinburgh. The paper appears in the last part of the 

 Society's Proceedings (vol. xx., pp. 53-62), accompanied by a map. 

 Dr. Munro concludes that the evidence of the existence of glacier 

 lakes furnished by the so-called " parallel roads " of Glen Roy, corres- 

 ponds, in its minutest details, with the facts observed in his study 

 of the recent lake in Norway. 



Various hypotheses have been started with reference to the 

 Dartmoor Granite, but the old view of De la Beche, that it was 

 intruded among the Devonian rocks and Culm-measures, into which 

 it sent veins, is supported in a recent paper by Lieut. -General C. A. 

 McMahon (Quart. Journ. Geol. Soc, vol. xlix., pp. 385-395). Such 

 veins have been observed by the author near Lydford, on the western 

 flank of Dartmoor. He also drew attention to the pseudo-bedding 

 of the granite, remarking that this conforms closely to the present 

 slope of the surface of the hills. In his opinion it may be attributed 

 to the action of the sun's heat and frosts, in rupturing the superficial 

 portions of the granite, and thereby producing the pseudo-bedding 

 and joints. 



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