LOWER SILURIAN OF CAPE BRETON — GILPIN. 171 



At Young's Brook, in St. Andrew's Channel, are found in thin 

 greenish and bluish slates impressions of an Obolella, and parts^ 

 of a trilobite, considered by Mr. Billings of Quebec group age. 

 Above McCormack's Road, in McLeod's Brook, are beds of com- 

 paratively unaltered slates, resembling Carboniferous grey and blu- 

 ish shales. These beds have yielded many specimens of Dictyonema, 

 Obolella, and an obscure Orthisina. Near Marion Bridge, on the 

 Mira River, light colored and gray and reddish sandstones yield 

 Obolella but of species diftering from those met on St. Andrew's 

 Channel. Mr. Fletcher writes : — Considered in regard to the 

 occurrence of animal life the contorted f elspathic shale, sandstone 

 and limestones found at the mouth of Mackintosh Brook, and on 

 the shore below Allan and Donald McAdam's, are of the highest 

 interest. Many of the shales are blackened with the impressions 

 of brachiopod shells, while some of the limestone is largely com- 

 posed of them. Among the shells there are numerous phosphatic 

 nodules, up to three-eighths of an inch in length. On examina- 

 tion they are found to consist of a fine bituminous paste, with 

 minute irregular grains of silicious matter aud fragments of 

 lingula, which is supposed to have formed the food of the 

 animals which produced the coprolities, and which, it has been 

 suggested, may have been some of the larger Trilobites. — These 

 coprolites are not uncommon in rocks of various ages. It is sup- 

 posed that the apatite deposits of Laurentian age, now worked 

 to some extent for the manufacture of fertilizers, were aggrega- 

 ted and crystallised from wide spread phosphatic nodules similar 

 to these but of much earlier date. Similar coprolites have been 

 observed at Arisaig in rocks of Upper Silurian age, and I have 

 seen them near Sutherland's River, in Pictou County, in strata 

 probably the continuation of the Arisaig rocks. They are not, 

 so far as yet observed, of economic value in Nova Scotia. 



McNeil's Brook, south side of Mira, is a good hunting ground 

 for fossils. Characterizing this horizon, Mr. Fletcher says ; 

 " Above McNeil's Mill the Brook exposes argillite and fine sand- 

 stone, including a bed of nodular bluish gray and black, bitumi- 

 nous, often granular, limestone, full of fossils, among which were 

 recognised Orthis, Obolella and the head of a trilobite. Above 



