181 



On the whole it seems better to hold to the prevalent English opinion 

 which places the line of the division above the Tremadoc, notwithstanding 

 the conditions that prevailed in Northern Europe, and notwithstanding 

 the fact that new and important genera of crustaceans appeared in the 

 Tremadoc slates. To adopt the line drawn by the palaeontologists of 

 Scandinavia and Germany would make necessary a revision of the Cam- 

 brian geology of America, whereby large areas and extensive faunas that 

 have been classed as Cambrian would of necessity be transferred to the 

 Ordovician, or Lower Silurian. Further, it may be inferred that this 

 hiatus in the faunas will be bridged over by the discovery of connecting 

 faunas in the strata of some other region than that of Europe. The Mount 

 Stephen fauna, for instance, in British Columbia, associates genera of 

 Ffestiniog, Dolgelly and Arenig types, and generally in the Rocky Moun- 

 tain region there is a blending of Cambrian and Ordovician types. For 

 these reasons it seems undesirable to abandon the old classification which 

 drew the dividing line at the base of the Arenig, and made the appearance 

 of the Arenig graptolites the starting point of a new system. 



The beds from which this fauna was taken appear in outcrops along 

 the left bank of McLeod brook, in Boisdale, Cape Breton, N.S., the best 

 locality being about an eighth of a mile below the bridge that crosses 

 that stream in McMullin settlement. The rock is a soft, fine-grained, 

 dark gray shale, not very different in appearance from that which, on the 

 opposite side of the valley of McLeod brook, carries the Dictyonema 

 fauna. The rock easily softens when exposed to the weather, but is 

 compact and firm lower down. The classes and phyla represented here 

 are Brachiopoda, Lamellibranchiata, Gasteropoda, Vermes and Crustacea. 



If one were to be governed by stratigraphical considerations alone, the 

 indications would rather place the Tremadoc fauna of McLeod brook 

 below the Dictyonema fauna than above it, as it lies to the north of 

 that fauna, and on the north side of the McLeod brook valley the lower 

 Cambrian strata are found, but the close folding of the measures and the 

 variable dips make the stratigraphy an unreliable guide for the minuter 

 groups within the divisions. We assume therefore that this fauna repre- 

 sents the highest portion of the St. John terrane present in Cape Breton. 



The following species described in this report, came from the Tremadoc 

 horizon. 



Urotheca. 

 Acrotreta sipo. 

 Leptobolus cf. linguloides. 



Bellerophon semisculptus. 



Parabolinella quadrata. { s ^cies of this 



P. cf. limitis. 



