RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 245 
The next formation, B, of Holtedahl’s section, consists of practically 
unfossiliferous shales and thin-bedded sandy limestone which passes 
above into By, sandy limestone and shale containing Coelosphaeridium 
cyclocrinophilum. In the upper part of the same formation is a large 
fauna which includes many species found in the Jewe of Esthonia. 
Cybele grewingki Schmidt, Chasmops marginata Schmidt, Porambonites 
schmidti Noetling, Coelosphaeridium cyclocrinophilum Roemer and 
Mastopora concava Eichwald are among the striking species which 
Holtedahl lists as common to the two regions. The thickness of this 
formation is unknown but it must be over forty meters. 
Then follow two very fossiliferous zones both characterized by an 
abundance of Cyclocrinites, and making a total thickness of about 
twenty-three meters. These formations have a fauna entirely com- 
parable to that in the Kegel of Esthonia. Holtedahl lists the follow- 
ing species found in both B; and the Kegel :— 
Basilicus kegelensis Schmidt, Chasmops maxima Schmidt, Chas- 
mops bucculenta Sjogren, Pterygometopus kegelensis Schmidt, Bucai- 
niella lineata Koken, Leptaena aff. schmidti Térnquist, Platystrophia 
biforata Schlotheim, Triplecia insularis Eichwald, Cyclocrinites oelandi- 
cus Stolley, C. vanhoeffeni Stolley, and C. balticus Stolley. 
Holtedahl correlated these latter zones, Bsa and Bsgb, with the 
Trinucleus shales of Sweden, the Trinucleus shales and Isotelus 
limestone of Norway, and the Kegel and Wesenberg of Esthonia. 
In regard to the correlation with the Trinucleus shales, Holtedah!] 
himself says that there are only two species, Illaenus linnarssoni and 
Remopleurides dorsospinifer common to the two. Neither of these 
species is a guide fossil, I//aenus linnarssoni in particular having a 
very long geological range. It is worthy of note that none of the 
Bohemian species which} make so important a part of the fauna of 
the Trinucleus zone of Sweden and the Christiania district is found 
in B; of the section in the Mjésen district, but the fauna is strictly of 
the Russian type and belongs to another basin. In this case, the 
difference can hardly be due to difference in facies, for the Trinucleus 
beds of the Christiania district contain a large amount of limestone; 
not a sandy limestone, it is true, but neither is the Kegel a sandy 
limestone. Furthermore, we are not here dealing with graptolites 
or other fossils highly sensitive to environmental conditions, but with 
general faunas. 
In Jemtland, the Trinucleus shales appear to be absent, and among 
the boulders of “Oestseekalk” are found many of the characteristic 
fossils of the Kegel and Wesenberg limestones, indicating that these 
