602 A. W. GRABAV LOWER ORDOVICIC FORMATIONS 



with Tetragraptus, Didymograptus, and Phyllograptus (Lower Deepkill 

 of America), and that this shale therefore replaces the Planilimbata 

 1 imestone. 



The Asaph us limestone immediately succeeding the Limbata limestone 

 in Sweden is the equivalent of a part of B III of Esthonia; hence the 

 zones B II (3 and B II y are wanting in Westergotlancl. and the lower 

 Middle Ordovicic hiatus (St. Peter hiatus) falls immediately above the 

 Limbata beds. The fossils of the Asaplms limestone, which serve to cor- 

 relate it with the East Baltic formations, are Megalaspis heros Dm., 

 which occurs in the raniceps and eichwaldi zones (B III (3 and B III y) 

 of Russia, Illcenus esmarkii Schloth, found in all three divisions of B III, 

 and Ampyx nasutus Dm., which occurs in B III a and the lower and 

 middle part of B III (3. Asaphus raniceps, the zone fossil of B III (3, is 

 represented in the Asaphus limestone of the Kinnekulle by variety 

 maxima Br. 



From these considerations it would appear that the Asaphus limestone 

 represents the middle and perhaps part of the upper division of the 

 Russian Orthoceras limestone (B III (3 and B III y a) . The absence of 

 Asaphus expansus certainly suggests the absence of the lower zone, B III 

 a, though this seems to be represented in the Christiania region (Ex- 

 pansus shale) and in Dalarne, where it rests on the Limbata limestone. 



That the line of division is not definitely drawn in the Kinnekulle 

 region is shown by the occurrence within the Asaphus bed there of Gyrto- 

 metopus clavifrons Dal., a form characterizing all three members of 

 Division B II in the South Baltic region. It is highly probable that the 

 part in which this is found belongs to the Limbata limestone, the extent 

 of which is thus equivalent to that of the Lower Reel Orthoceras limestone 

 as held by G-. Holm. 



The Gigas limestone of Westergotlancl may represent the upper part of 

 B III y or the lower part of C I a. This latter division includes the 

 Platyurus limestone, as shown by the presence of Asaphus platyurus A., 

 while the Chiron limestone, with Illcenus chiron Hm., represents the 

 horizon C I /? of the East Baltic region. The succeeding Chasmops lime- 

 stone probably represents the remainder of the Echinosphasrites bed or 

 C I y of the Baltic region, and perhaps C II as well. It contains Ampyx 

 rostratus Sars., which ranges from C I (3 to C II and Echinosphcerites 

 aurantium Gyllenh.. which ranges through all divisions of C (Echino- 

 sphaerites, Kuckers, and Ifter beds), and is reported from the J ewe and 

 Wassalem beds (D I and D III) as well. 



The Trinucleus shale following this series of limestones contains a 

 fauna which has no representation in the East Baltic region, and the 



