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 Paradoxides 
oelandicus. 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 Dictyonema 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 Dictyonema 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 aurantiwm 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- 
cistroceras undulatum Boll, Remopleurides, Ptychopyge, Nileus arma- 
dillo, Illaenus chiron, and Orthoceras. 
Chiron limestone. This is a limestone containing Illaenus chiron 
Holm, Ptychopyge aciculata Ang., P. testicaudata Steinh., Megalaspis 
pagiata Tqst., Ogygiocaris dilatata sarsi Ang., Telephus bicuspis Ang., 
Iituwites lituus. Monf., and Didymograptus geminus His. 
Platyurus limestone. This zone has only a few fossils reported, 
these being Asaphus platyurus maximus, Ptychopyge brachyrachis 
Remele, Rhynchorthoceras cf. angelini Boll:, Echinosphaerites auran- 
tuum Gyllenhahl, and Hyolithes inaequistriatus Remele. 
From the Gigas limestone, only Megalaspis 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 tumidus, 
Asaphus sp., Illaenus esmarki, I. centrotus, Nileus armadillo, and 
Niobe frontalis as among the species present. 
