ARCTIC ORDOVICIAN AND SILURIAN CEPHALOPODS 255 
The species listed by Wyatt-Edgell as Endoceras eoum and 
described by Blake as Orthoceras {Conoceras) eoum, from , the 
Arenig of Shelve, in the western part of Salop county, in Wales, 
also has a Canadian aspect. The siphuncle is marginal and 
equals two-sevenths of the diameter of the conch. On reaching 
the siphuncle the septa ^^bend slightly upward toward the aper- 
ture; though the chambers here stop short, the septa are con- 
tinued over the siphuncle slightly bending upward, and along 
the latter is a depressed line.” On the relationship of this 
species Blake adds: ^‘This can not be an Endoceras, as the septa 
certainly do not make sheaths pointing backwards.” Appar- 
ently this shell bears some resemblance to Ellesmeroceras scheii 
described in the present paper from Bache Peninsula. 
Such species as Actinoceras cochleatum (Schlottheim) , Endo- 
ceras festinans Blake, and the form identified as Endoceras 
hrongniartii Troost suggest the Black River age of the Bala beds 
of Great Britain. The Llandeilo fauna of the Girvan district 
also contains American elements, such as Maclurites logani, a 
typical American Black River form. 
On continental Europe, however, in the Scandinavian-Baltic 
areas, Ordovician faunas quite distinct from the American types 
prevail, as though some barrier had intervened, forming an 
eastern limit to the American Ordovician seas. 
These conclusions are expressed by Dr. Holtedahl in the 
following terms: 
In the Bear Island a fauna occurs of which we can say that it is no 
more closely connected with the Scandinavian-Esthonian than are the 
American equivalent faunas themselves. In the writer’s opinion this 
fact gets its most probable explanation by assuming a land barrier 
between two different districts of sedimentation of middle Ordovician 
time, the one characterized by an American-Arctic, the other by a 
Scandinavian-Baltic faunal element. The many facts pointing towards 
the existence — at a corresponding time — of a land mass to the north- 
west of the northernmost, stiatigraphically more fully known districts 
of Southern Norway and Sweden, the Mjosen district in Norway and 
Jemtland of Sweden, support this supposition. In Scotland a land is 
generally assumed to have been present in middle Ordovician time in 
