RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 217 



Finally at the northern end of the island, the Ordovician rests on strata 

 of the lowest of the Middle Cambrian zones, that with Paradoxidcs 

 oclandicus. This section shows very clearly that there was an uplift, 

 tilting, and erosion after the deposition of the Peltura beds of the 

 Upper Cambrian and before the deposition of the Dietyonema shales 

 of the Ordovician, and thus^emphasizing once more that the natural 

 place to draw the boundary between the Ordovician and Cambrian is 

 at the base of the Dietyonema shales (or the equivalent Obolus sand- 

 stone). 



In spite of the considerable amount of work which has been done on 

 Oeland, I am unable to find that any section has been published in 

 which the thicknesses of all the strata have been given. 



The youngest strata found in place in Oeland belong to the Lower 

 Chasmops or Echinosphaerites limestone, but the Macrourus lime- 

 stone, Trinucleus shale, and Leptaena limestone (Lyckholm) are all 

 represented by numerous boulders. 



The Echinosphaerites limestone is seen only in northern Oeland, 

 and only Echinosphaerites auraniium and Illaenus chiron seem to be 

 reported from it. 



The Orthoceras limestone is very well developed on the island and 

 it was here that its subdivision on the basis of fossils was first accom- 

 plished by Moberg (71). The zones, in descending order are: — 



Ancistroceras limestone. The fauna is reported to contain An- 

 cisfroceras uudidafum Boll, Remopleurides, Ptychopyge, Nileus arma- 

 dillo, Illaenus chiron, and Orthoceras. 



Chiron limestone. This is a limestone containing Illaenus chiron 

 Holm, Ptychopyge aciculata Aug., P. testicaudata Steinh., Mcgalaspis 

 pagiata Tc^st., Ogygiocaris dilatata sarsi Ang., Telephus hicuspis Aug., 

 Lituites lituus Monf., and Didymograptus geminus His. 



Platyurus limestone. This zone has only a few fossils reported, 

 these being Asaphus platyurus maximus, Ptychopyge hrachyrachis 

 Remele, Rhynchorthoceras cf. angelini Boll., Echinosphaerites auran- 

 tium Gyllenhahl, and Hyolithcs inaequistriatus Remele. 



From the Gigas limestone, only Mcgalaspis gigas Ang. has been 

 reported. 



Upper Asaphus limestone. Moberg states that this is a reddish, 

 rarely white, crystalline limestone with a large fauna of small, mostly 

 undescribed trilobites, and that there is nothing elsewhere which 

 exactly corresponds to this zone. He cites Nieszkowskia tumulus, 

 Asaphus sp., Illaenus csmarki, I. centrotus, Nileus armadillo, and 

 Niobe frontalis as among the species present. 



