BALTIC REGION 595 



beds of Dalecarlia, Sweden, is shown by Megalaspides schmidti, the rep- 

 resentative of M. dalecarlicus of the limestone bands of the Swedish 

 Phyllograptus shale. Finally, Orthoceras atavus Brogger is another char- 

 acteristic species of the Ceratopyge limestone, having first been described 

 from that rock in Norway. 



Altogether it would appear that Division B I of the Baltic Provinces 

 is the equivalent of the Scandinavian Ceratopyge limestone and shale, 

 forming the near-shore phase of that division of the North European basal 

 Ordovicic. This is borne out by the fact that this horizon is absent in 

 the Bohemian area, where, however, its time equivalent may be repre- 

 sented by the Krusnahora sandstone with Lingula feist mantelli, a fauna 

 probably of Atlantic origin. Ceratopyge has, however, been reported 

 from the Thuringian forest region. 28 Lamansky holds that Division B I 

 may be in part the equivalent of the Lower Phyllograptus shales, as 

 shown by the fact that these shales contain limestones with Megalaspides, 

 a genus also represented in B I ft. For this horizon he proposes the name 

 Megalaspides zone and places it between the Ceratopyge and the Plani- 

 limbata zones. 



It may be desirable to repeat here the statement made above, that the 

 Ceratopyge fauna is of Siberian origin, entering the Baltic region from 

 the northeast, whereas the Dictyonema and Phyllograptus-Tetragraptus 

 faunas are of Atlantic origin (or habitation), entering the same province 

 from the west. Thus an overlapping of the faunas occurs, though, as 

 found in Scandinavia, the Dictyonema always underlies the Ceratopyge 

 beds, a circumstance which clearly shows that the Ceratopyge fauna en- 

 tered this region subsequent to the arrival of the Dictyonema fauna, 

 though it probably existed at the same time in the more easterly provinces. 



Since the Phyllograptus shales normally follow on the Dictyonema 

 shales, where the Ceratop} r ge beds are absent, they are to be regarded as, 

 in part at least, the equivalent of the Upper Ceratopyge beds, though a 

 portion of the latter may also be represented by Dictyonema shale. The 

 fact that the Phyllograptus shales disappear eastward and northward 

 ((Edegarden, in Westergotland, and Sjurberg, in Dalarne), while they 

 are present westward (Kinnekulle, Christiania), where the Planilimbata 

 limestone is absent, shows the derivation of the graptolite fauna to be 

 from the west or Atlantic region. 



The North Pacific or Siberian habitation of the Ceratopyge, as well as 

 the Megalaspis faunas, is further shown by the recent discovery by Wal- 

 cott 29 of Ceratopyge canadensis in the Lower Goodsir formation of British 



28 H. Loretz : Jahr. Preuss. Geol. Landesanst., 1881, p. 175. 



20 Cambrian Geology and Paleontology, vol. ii, No. 7, 1912. The correct generic de- 

 termination of this trilobite has, however, been questioned. 



