Vol. 50.] OLENELLUS-ZONE OP THE NORTH-WEST HIGHLANDS. 661 



41. Additions to the Fauna of the Olenellus-zone of the North- 

 west Highlands. By B. N. Peach, Esq., F.R.S., F.G.S., of 

 the Geological Survey of Scotland. (Communicated by per- 

 mission of the Director-General of the Geological Survey. 

 Bead June 20th, 1894.) 



[Plates XXIX.-XXXIL] 



Contents. 



Page 



I. Introduction 661 



II. Description of a new Sub-genus and some new Species of Trilobites . . . 662 

 III. Theoretical Considerations based upon the Study of the Remains 



described 671 



I. Introduction. 



It is now two years since Mr. Home and I communicated to this 

 Society details of the discovery by the Geological Survey of Olenellus 

 in the ' Fucoid Beds ' and Serpulite Grit of the west of Ross-shire, 

 which in our opinion proved the Lower Cambrian age of those strata. 

 The discovery has been followed up by the Survey, and through 

 the kindness of Major Bobertson, the shooting tenant, and of 

 Mr. A. P. Burves, the agent for Mr. Mackenzie, the proprietor of 

 the Dundonnell Forest, facilities were afforded to Mr. A. Macconochie, 

 Fossil Collector of the Survey, which allowed him to make a more 

 exhaustive search of the localities mentioned in our paper. The 

 search resulted in his obtaining a considerable amount of new 

 material. 



While the work of the Survey was advancing in the region around 

 the head of Loch Maree, prior to the discovery of Olenellus at 

 Dundonnell, certain outcrops of the ' Fucoid Beds ' were considered 

 fossiliferous, and were accordingly marked off to be further searched 

 by the collector. One of these, situated in Glen Cruchallie, more 

 commonly, though erroneously, known as Glen Logan, yielded 

 Mr. Macconochie specimens of Salterella and Hyolithes, but no 

 recognizable fragments of trilobite. The other outcrop, noticed by 

 Mr. Greenly, occurs on the northern slopes of Meall a' Ghubhais at 

 a height of between 1200 and 1300 feet, just over the tree-line, 

 and about 4 miles north-west of Kenlochewe. As this locality is 

 situated in the Sanctuary, or most carefully preserved part of the 

 Kenlochewe Deer Forest, it could not be searched when Mr. Mac- 

 conochie's services were available, owing to the approach of the 

 stalking season. 



Early in the field-work of last year, Messrs. Home, Gunn, and 

 Clough had occasion to visit this locality, in order to study the 

 effects of movement on different members of the Torridonian Series, 

 which have there been thrust over the Cambrian rocks and left as 

 an outlier by denudation to form the upper part of Meall a' Ghubhais. 



,2z 2 



