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xlviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. J 



in re-examining the northernmost counties of Scotland, on which 

 twenty-eight years ago he and his companion Prof. Sedgwick had shed 

 much Hght, Sir Roderick Murchison has endeavoured to determine 

 the true relations of the crystalline rocks in the Highlands in which 

 organic remains had been discovered by Mr. Peach, to the great 

 deposit of the Old Red Sandstone. 



After pointing out the general characters of the crystalline rocks 

 of Sntherlandshire, and showing how they consist of regularly strati- 

 fied masses of siliceous, calcareous, and schistose bands, which are very 

 slightly affected by any slaty cleavage, he affirms that the limestones 

 containing the fossils are really part and parcel of those ancient 

 masses. But whilst the organic remains seem to belong to Euom- 

 phali, Lituites ?, and Orthoceratites, their state of preservation is too 

 imperfect to admit of their specific determination. 



In reference, however, to their relations, he declares it to be his 

 belief, that they are of a date certainly anterior to the Old Red Sand- 

 stones, the basement conglomerates of which wrap round the crystal- 

 line rocks, are made up in great measure of their fragments, and are 

 seen to overlap their edges in discordant positions at several localities 

 in the western part of Ross-shire. The flagstones and schists of Caith- i 



ness, with their ichthyolites and fossil plants, are, as indicated long ago ^ 

 by himself and Prof. Sedgwick, in a still higher position. 



Adverting to the vast dimensions and varied composition of the 

 Old Red of the northern Highland counties. Sir R. Murchison re- 

 asserts what he put forth prominently in his work * Siluria,' that the 

 great tripartite group of the Old Red Sandstone, as developed in the 

 north of Scotland, is a full and entire equivalent of the Devonian 

 rocks of other parts of Europe. 



Another interesting paper was communicated to the Geological 

 Section of the British Association at Glasgow, by Mr. Salter, " On the 

 recent discovery of Fossils in the Cambrian Rocks of the Longmynd." 

 These rocks, of which the author of this paper has given a mineralo- 

 gical description, were hitherto considered to be azoic, and to mark 

 that geological period when, before the introduction of organic life, 

 sedimentary rocks were first deposited in the ancient seas on the 

 hardened surface of the earth. It would now appear, from Mr. 

 Salter's discoveries, that in these most ancient beds, some small but 

 unequivocal traces of organic life are to be found. These traces 

 consist partly of numerous double oval impressions on the surface of 

 the ripple-marked sandy beds. They are not above a line in length, 

 are always placed in pairs, and parallel to one another in direction, 

 although scattered over the stone. As they are not placed in regular 

 series, they cannot indicate the track of a crustacean ; they are sup- 

 posed to offer the best analogy with the double holes of sand-burrow- 

 ing worms (Arenicola), and have therefore been called by the author 

 Arenicola didyma. Besides these, there are many distinct traces of 

 the presence of worms in long sinuous tracks, such as are usually 

 made by these animals. 



But by far the most interesting fossils are several specimens of 

 portions of the tail, and perhaps the head, of a new genus of Olenoid 



