368 



PJiOCEEDIXGS OF THE GEOLOGICAL SOCIETY. [DcC. 1, 



of the hill, then rises high upon the truncated edges of the Cam- 

 brian rock, and even caps one of the summits of the noble Queenaig. 

 The lower beds of the quartz-rock, which rest upon the Cambrian 

 sandstone, are here very striking, from exhibiting on their surface 

 large round knobs on the tops of cylindrical bodies which pass 

 through several layers and are unquestionably the infillings of ex- 

 cavations made by Annelides. (See PL XIII. figs. 29, 30.) The 

 quantities of these pipe- shaped bodies are astonishing ; and as they 

 also occur in the same stratum (^. e. near the base of the lower 

 quartz-rock) and on the west shore of the Kyle of Durness, we may 

 infer that they are the oldest vestiges of hfe which can be detected 

 in the Lower Silurian rocks of the I^^orth Highlands. 



In illustration of the manner in which these tubular bodies tra- 

 verse the layers of quartz-rock or crystallized sandstone on the north- 

 eastern flank of Queenaig, I may here repeat a woodcut from p. 41 of 

 ^ Siluria ' (new edit.), representing Annelide-burrows in the quartz- 

 rock of the Stiper Stones, a well-known Lower Silurian rock of 

 Shropshire. The trumpet-shaped openings, sometimes 2 or 3 inches 

 in diameter, the tubular cavities, and the cylindrical casts (identical 

 with forms found thirty years ago on the west shore of the Kyle of 

 Durness by Sedgwick and myself), leave no room for doubt that they 

 also represent the Annelides of the English Stiper Stones and of the 

 Potsdam Sandstone or Lowest Silurian rock of North America (Sco- 

 lithus linearis of Hall). 



Pig. 5. — Fossil Annelide-tuhes (Scolithus linearis) from the Stiper 

 Stones, resembling those from Assynt. (Prom ' Siluria,' new edit, 

 p. 41.) 



Descending into the Yale and Loch of Assynt, upon the surface of 

 the lower quartz-rock, its upper layers are clearly seen to become 

 more schistose and shaly, and also to exhibit fucoidal and other 

 impressions. Then the succeeding limestone expands in terrace over 

 terrace, and is best exposed in mounting from the edge of the loch, 

 or from the west by north, to the hill called Cnoc-an-drein, on the 

 east by south. In this walk you pass over a succession of parallel 

 ridges for the space of about three-quarters of a mile, each cal- 

 careous band dipping easterly at about 25°. Some of the limestone 

 is of deep-grey or dull-blue colour; other parts are light-grey, 



