NORTH SCOTLAND 569 



DISCUSSION 



Of these 60 species, 3 (numbers 7, 9, and 10) are reported from the 

 Lower Cambric. These include one trilobite, doubtfully identified, and 

 two brachiopods. The trilobite was not to be found in the Edinburgh 

 collection ; the brachiopod identified as Camarella (Sivantonia) antiquata 

 Bill, is a small inner mold, with characters inconclusive. Walcott does 

 not cite it from the Durness limestone in his revision of that species. 

 The same is true of Orthisina (Nisusia) festinata Bill. Of the identified 

 species, 29, or 4-7.5 per cent, occur in the Beekmantown of eastern Canada 

 or New York; 5, or about 8.5 per cent, occur in beds referred to the 

 Chazy in Newfoundland, but which may also belong to tlin Beekmantown; 

 5, or about 8.5 per cent, are found in the Black River beds of America, 

 and 4, or about 6.5 per cent, in the Trenton and higher beds of the 

 American Ordovicic. 



In spite of the 25 per cent of species identified with Chazy or younger 

 American forms, the fauna is probably a unit, for the material identified is 

 as often as not from the lower of these beds. It is not impossible, how- 

 ever, that the higher part of the Croisaphuill group may include a Chazyan 

 horizon, there being in that case u hiatus between the Chazyan and the 

 Beekmantown portion of this group. The only fossils listed from the 

 Durine group are Tlormoioma gracilis, a typical American Black River 

 to Richmond species, and 11. graciiima Salter. This series may represent 

 Black River or younger Ordovicic horizons of the East American type. 

 It should, however, be remembered that the preservation of these forms 

 is generally such as to render absolute identification difficult, if not im- 

 possible. 



As has been stated, the Scottish series finds its counterpart in the 

 deposits of western Newfoundland, as shown at Bonne Bay, Table Head, 

 and Cowhead. The lower part of this series, including divisions A-C, 

 with a total of 2,020 feet, represents the Lower Cambric and carries the 

 Olenellus fauna. This part is therefore the analogue of the Eriboll 

 quartzites and the Serpula grits of northern Scotland. Divisions D to II, 

 inclusive, with a thickness of 1,839 feet, represent the Beekmantown. 

 The contact between D and C is shown in Bonne Bay, but its detail has 

 not been worked out. From 250 to 300 feet below the top of Division C. 

 as defined by Logan and Billings, occurs a white quartzite in beds of 

 from 2 to 3 feet thick and interstratified with pyritiferous magnesian 

 limestones, which constitute one-fourlh of the mass. This quartzite may 

 mark the actual contact and conceal the hiatus between the Lower Cambric 

 and the Lower Ordovicic strata. The beds below this sandstone are 

 shales and limestones carrying the Olenellus fauna, while those above are 



