3IO 



Correlation with the European faunas are not readily 

 made, and until the Arisaig faunas have been completely 

 studied there would appear to be little value in making 

 the attempt in any great detail. 



The presence in the Ross Brook fauna of Dalmenella 

 elegantula, Leptaena rhomboidalis , Plectamhonites trans- 

 ver sails, and Anoplotheca hemispherica indicates for this 

 and the Beach Hill Cove formation a probable time 

 equivalency with the Lower Llandovery of north Europe. 



The highest beds of the McAdam formation contain 

 Monograptus riccartoensis and Spirifer crispus, both of 

 which are characteristic of the north European Middle 

 Wenlock, and their common presence would lead to the 

 reference of the highest beds of the formation to Middle 

 Wenlock time while the great body of the formation 

 should probably be placed in the Upper Llandovery, 

 Other fossils common to the Upper Llandovery and the 

 McAdam formation are Dalmanella elegantula, Leptaena 

 rhomboidalis, Atrypa reticularis and Calymene tuberculata, 

 all of which, however, also occur in the Wenlock. 



The Moydart formation is marked by the earliest 

 appearance of Chonetes novascoticus , which suggests, 

 but is smaller than the European C. striatella; Wilsonia 

 wilsoni (Ludlow of Norway, Wenlock and Ludlow of 

 England) ; and Spirifer siihsulcatus, a form of the S. crispus 

 type but larger. Calymene tuberculata and Leptaena 

 rhomboidalis are also present. The fauna is one suggesting 

 an approach to the Ludlow, but still within the Wenlock. 



The abundance of large Chonetes of the C. striatella 

 type, Rhynchonella nucula, and Schuchertella pecten indicate 

 for the Stonehouse formation an horizon equivalent to 

 the north European Ludlow. 



Deionian. — The Knoydart formation contains the re- 

 mains of ostracoderm fishes whose closest generic rela- 

 tionships, as stated by Woodward, are with those occurring 

 in the Old Red Sandstone of Europe. This indicates 

 a lower Devonian age for the Knoydart strata. Their 

 age can be determined, although less definitely, by another 

 line of reasoning. The period of faulting in which the 

 great fault of the Hollow was formed, is post-Knoydart 

 and pre-Mississippian, since the rocks of the former are 

 involved and those of the latter cross the fault. To the 

 northwest before the close of Devonian time occurred 

 disturbances which are expressed in the folds and faults 



