338 bulletin: museum of comparative zoology. 



The most diagnostic fossil in the Tamsal formation is Pentamerus 

 borealis. In the Kristiana region, this is confined to the upper portion 

 of Kiaer's zone 6c and to 7a, that is, to the uppermost zone of the 

 Norwegian Lower Llandovery and the lowest zone of the Upper 

 Llandovery, where it is associated in the latter zone with Bilobites 

 hilobus, and in the former with Plectambonites quinquecostata McCoy 

 (probably a different species since McCoy's form came from the 

 Ordovician), Coelospira hemispherica, Stricklandinia lens Sowerby, 

 and Camarotoechia decemplicata (Sowerby); all of which in the same 

 or closely identical species make their first appearance in the upper- 

 most zone of the Gun River formation, and this fact points to the 

 probability that this zone, and probably some parts of the preceding 

 zones, represent the Tamsal formation in the Anticosti section. If 

 this view be correct, it follows that the equivalent of the Becsie River 

 formation is not present in the Russian Silurian of the Baltic, and 

 hence there is a considerable time break between the Borkholm and 

 Jorden beds. It is worthy of note that the faunal break at this point 

 is far greater than that between the Lyckholm and Wesenberg. 



From one locality a small collection was made which in the field 

 reminded me of the Cataract fauna, but until this collection has been 

 studied and compared it is thought best to place no emphasis upon it. 

 At any rate, it would not depreciate the correlation just made. 



The St. Johannis formation is almost certainly the equivalent of 

 the Wenlock of Scandinavia, England, and west Europe generally, 

 and the Rochester and Niagara of North America. With the Wen- 

 lock of Norway, Kiaer's zones 8a to 8d, the formation has at least 

 twenty-eight species in common, of which the more diagnostic are 

 Palcocyclus porpila, Thecia sivindernana, Camarotoechia borealis, 

 Cyrtia exporreda, Dalmanella eleganhda, Dinorthis rustica, Eospirifer 

 radiatus, Meristina tumida, Rhipidomella hybrida, Rhynchotreta cuneata, 

 Spirifcr crispus, Wilsonia ivilsoni, Omphalotrochus discors, Calymene 

 tuberculata, Encrinurus punctatus, and Bumastus barricnsis. Corre- 

 lation of the St. Johannis formation is therefore made with stage 8 

 (Wenlock) of the Norwegian sections. Since many of the fossils to 

 which reference has been made in this paragraph also occur in the 

 lower zones of Kiaer's stage 9 (Lower Ludlow) it is possible that the 

 upper portion of the St. Johannis formation may find an equivalence 

 in the lower portion of stage 9. 



With the English Wenlock or Salopian series, the St. Johannis 

 formation has nearly the same species in common as it has with the 

 Norwegian section as well as some additional species and the correla- 



