Notices of Memoirs — Sir A. Oeikie — N. W. Highlands. 499 



me tbis remarkable zone, I was struck witb tbe singularly unaltered 

 cbaracter of tbese sbales, and agreed witb bim tbat, if fossils were to 

 be looked for anywbere among those ancient rocks, tbey should be 

 found here, and that tbe fossil collector, Mr. Arthur Macconocbie, 

 should be directed to search the locality with great care. The 

 following week this exhaustive search was undertaken, and Mr. 

 Macconocbie was soon rewarded by the discovery of a number of 

 fragmentary fossils, among which Mr. B. N. Peach, who was also 

 stationed in tbe district, recognized what appeared to bim to be un- 

 doubtedly portions of Olenellus. The importance of this discovery 

 being obvious, the search was prosecuted vigorously, until the fossil- 

 iferous band could not be followed further without quarrying opera- 

 tions, which in that remote and spa,rsely inhabited region could not 

 be at tbat time undertaken. The specimens were at once forwarded 

 to me, and were placed in the bands of Messrs. Sharman and Newton, 

 Palaeontologists of the Geological Survey, who confirmed the refer- 

 ence to Olenellus. More recently Mr. Peach and Mr. Home, in a 

 renewed examination of the ground, have found, in another thin 

 seam of black shale interleaved in the ' Serpulite grit,' additional 

 pieces of Olenellus, including a fine bead-shield with eyes complete. 

 There may be more than one species of tbis Trilobite in these Ross- 

 shire shales. The specific determinations and descriptions will 

 shortly be given by Mr. Peach. 



The detection of Olenellus among tbe rocks of tbe North-west 

 Highlands, and its association with the abundant Salterella of tbe 

 ' Serpulite grit,' afford valuable materials for comparison with the 

 oldest Palaeozoic rocks of other regions, particularly of North 

 America. Tbe ' Fucoid beds ' and ' Serpulite grit ' which intervene 

 between the quartzite below and tbe Durness Limestone above are 

 now demonstrated to belong to the lowest part of tbe Cambrian 

 system. The quartzites are shown to form the arenaceous base of 

 that system, while the Durness Limestones may be Middle or Upper 

 Cambrian. On the other band, the Torridon Sandstone, which 

 Murcbison placed in the Cambrian series, can now be proved to be 

 of still higher antiquity. The marked unconformability which 

 intervenes between it and the overlying quartzite points to a long 

 interval having elapsed between tbe deposition of the two discordant 

 formations. The Torridon Sandstone must therefore be pre-Cam- 

 brian. Among the 8,000 or 10,000 feet of strata in this group of 

 sandstones and conglomerates, there occur, especially towards the 

 base and the top, bands of grey and dark sbales, so little altered 

 that they may be confidently expected somewhere to yield recogniz- 

 able fossils. Already my colleagues have detected traces of annelids 

 and some more obscure remains of other organisms in these strata. 

 These, tbe oldest relics of life yet known, have excited a vivid desire 

 in the Geological Survey to discover further and more determinable 

 fossils associated with them in the same primeval resting-place. We 

 shall spare no pains to bring to light all tbat can be recovered in 

 the North-west Highlands of a pre-Cambrian fauna. 



