230 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
graptoides zone succeeds the Ceratopyge zone, and precedes the Lim- 
bata limestone. The Planilimbata limestone can not be older than 
the oldest of the Tetragraptus zones. On Oeland, Isograptus gibber- 
ulus, and other graptolites of the Lower Didymograptus zone occur 
in the Lower Asaphus limestone, which Lamansky correlates with the 
Russian zone B,,;g. In Norway the Gigas limestone is followed by 
black shale with Didymograptus geminus. On Oeland, the Gigas 
limestone is followed by the Platyurus limestone, and that in turn by 
the Chiron limestone, which contains Didymograptus geminus. The 
top of the Gigas limestone, and likewise of the Orthoceras limestone 
(B,:1,) of Russia, is therefore somewhat older than the Didymograptus 
geminus fauna. In Scania, the Didymograptus geminus fauna is found 
in shales resting on other shales containing Phyllograptus cf. typus and 
Didymograptus cf. bifidus. This in turn rests upon the Orthoceras 
limestone of that region. This limestone, in turn follows shale with 
the Isograptus gibberulus fauna. The limestone contains a large 
trilobite fauna which, however, in our incomplete knowledge of the 
faunas of the Swedish “Orthoceras limestone,” it is not safe to corre- 
late directly with the faunas of other regions. Since it follows the 
zone with Isograptus gibberulus, one would naturally correlate the 
Orthoceras limestone of Scania with the Lower Asaphus limestone of 
Oeland. If this correlation is correct, then the Phyllograptus cf. 
typus beds of Scania would appear to represent some or all the Upper 
Asaphus limestone, Gigas limestone, and Platyurus limestone of 
Oeland. But for reasons to be given later, the Platyurus limestone is 
probably to be eliminated from this list. This does not of course, 
prove definitely that the Gigas limestone is of the age of Phyllograptus 
cf. typus, though there is a strong presumption, since both are older 
than the zone with Didymograptus geminus. Fortunately however, 
Schmidt found Phyllograptus in B,,, in Esthonia, and Phyllograptus 
sp. has been reported from above the Gigas limestone of Norway. 
The limestone of the Gigas and lower zones, down to the bottom of 
the Planilimbata zone of Sweden, and the zones B,, and B,,, of Russia 
must therefore be placed within the range of Phyllograptus in the 
graptolite succession. It remains now to see what that means in the 
American sequence. 
The occurrence of the Tetragraptus-Phyllograptus-Didymograptus 
fauna in the shales of the Lévis formation of Canada has long been 
known, and recent work by Ruedemann (115) and the writer (111) 
has shown the order of succession of the faunules within the forma- 
tion. The relation of the Lévis to the Beekmantown of America 
