174 Revieics — Geological Surrey of Scotland. 



member of wliicb is a fine sericite schist, occasionally becoming 

 calcareous with subordinate beds of finely banded greywackes and 

 quartzites, both of which contain traces of annelid burrows. The 

 otber member of this zone is a fine black graphitic schist, which 

 occurs upon a horizon higher than the sericite schist, and marks the 

 top of this group. Like the other calcareous and argillaceous zones, 

 it seems to represent a maximum of depression beneath the waters 

 of the ocean. 



The traces of annelid tubes which have been found in this zone 

 were discovered by the Duke of Argyll 1 and myself, 2 His Grace 

 finding his specimens behind the castle at Inverary, my own being 

 found on Craig Na Challeich, a mountain above Killin, Perthshire. 

 The beds in which the Duke found his specimens are described by 

 him thus : " The comparatively thin beds in which the annelid 

 tubes are found at Inverary are by no means the lowest in our series. 

 They are underlain and overlain by a great number of beds, both 

 slaty and siliceous, but the great mass is slaty, with a highly 

 developed micaceous character." The annelid tubes were thus found 

 in a thin band of quartzite, intercalated in a series of highly 

 micaceous schists, which exactly corresponds to the character of the 

 rocks where I found my own on Craig Na Challeich — that is, in the 

 upper argillaceous zone. Further, in his map of Scotland, published 

 in 1892, Sir A. Geikie 3 colours the rocks in which His Grace found 

 his specimens as the same as those occurring on Craig Na Challeich, 

 so that I have no hesitation in believing them to be the same beds, 

 and that these annelid tubes mark a distinct horizon in these 

 Highland rocks. 



This zone, like the others just described, is found to have a similar 

 geographical distribution across the whole of the Southern Highlands. 

 In Perthshire I have traced it at Tyndrum, where it is faulted against 

 a series of quartzites. Further east, on the high ridge above Loch 

 Tay, it is found occupying its normal position above the middle 

 arenaceous group, stretching through the peaks of Craig Na Challeich, 

 Ben Cruben, Ben Lawers, and thence eastwards by Killiecrankie and 

 the Spittal of Glenshee. 



. (To be continued.) 



EEYIB "W S. 



I. — Memoirs of the Geological Survey of Scotland: Ex- 

 planation of Sheet 5. By John Horne, F.B.S.E. ; with the 

 collaboration of B. N. Peach, F.R.S., and J. J. H. Teall, F.R.S. 

 (Edinburgh : printed for Her Majesty's Stationery Office by 

 Neill &Co., 1896. 8vo, pp. 71, with 5 illustrations. Price Is. Gd.) 



SHEET 5 of the Geological Survey Map of Scotland includes a 

 large portion of Kirkcudbrightshire, being the country around 

 Castle Douglas, Dalbeattie, Kirkcudbright, and Gatehouse-of-Fleet. 



> "Bodies of Organic Origin" : Eoy. Soc. of Edinburgh, 1888-9, p. 40. 



2 Trans. Perthshire Soc. of Nat. Sci., vol. i, p. 11(5. 



3 Map of Scotland, 1892. 



