Reviews—The Tremadocian of Sweden. 87 
This scheme is in all essentials in complete agreement with the 
conclusions which I shall express in another place, and is particularly 
satisfactory to British geologists in that by the inclusion of the 
Boeckia and Acerocare zone within the Ceratopyge regio the lower 
limits of that regzo and of the Tremadoc Slates of Britain become once 
more identical. «Ihe weakest link in the scheme seems to be the 
presumed contemporaneity of the Apatocephalus-bearing Ceratopy gekalk, 
with the graptolite shales with Zetragraptus phyllograptoides. The 
only direct evidence put forward for this contemporaneity is that about 
Hunneberg in Vestergétland Moberg and von Schmalensee found in 
1892 a 2-3 inch band of nodular glauconitic limestone containing 
Symphesurus and Megalaspis occurring above the TZetragraptus 
phyllograptoides beds, and they consider that this must be regarded as 
the Apatocephalus serratus zone. In my own examination of the same 
section last Semmer, however, I found that both the basal member of 
the paler grey shales which underlie the graptolite beds and the 
highest bank of the dark pyritous ‘jernberg’ contain Apatocephalus ; 
and though I am willing to admit that the greater part of the. 
‘jernberg’ contains a fauna more like that of the Ceratopygeskiffer of 
Norway than that of the Ceratopygekalk of either Oland or Skane. 
I am not at all prepared to regard that evidence as convincing proof of 
the replacement of the Apatocephalus zone by Tetragraptus shales. 
The indirect evidence that graptolite beds are generally absent where, 
as in Oland and Ostragitland, the Ceratopygekalk is best developed is 
certainly striking, but even there 7. phyllograptoides beds might just 
as well be represented by Planilimbatenkalk as by the Ceratopygekalk 
with Apatocephalus. In eastern Skane too the zone of 7. phyllograptoides 
is quite well developed, and, as shown by Linnarsson, Holst, and 
Westergard, is underlain by pale glauconitic and brachiopod-bearing 
shales and limestone nodules which may well be the Apatocephalus beds 
themselves. In the Kristiania district the 7. phyllograptoides fauna 
does not seem to have been recorded, but, unless I am much mistaken, 
the graptolitic beds which come nearest to the glauconitic Cerato- 
pygekalk at Gjeitungholmen in Kristiania Fjord may with great 
probability be referred to some part of that zone, and are interbedded 
with limestone bands very like the upper nodular limestone of 
Hunneberg discussed above. If, however, Professor Moberg and 
Dr. Segerberg will admit, as they seem to suggest on p. 44, that the 
Ceratopyge regio shall include some part of the Oland Planilimbatenkalk, 
the inclusion of the Zetragraptus phyllograptoides beds will, I think, 
be justified, and the upper limit of the Tremadocian as so defined, 
though somewhat arbitrary in its conception, will at least have the 
great advantage that it can be recognized and traced over wide areas 
and through all kinds of sediments. The effect of such a change of 
nomenclature upon British literature would be hardly noticeable, for 
except among the Durness Limestone of North Scotland and in the 
Lake Country the beds affected are represented only by an unconformity. 
The inclusion of Miss Elles’ Lower Zetragraptus beds of the Skiddaw 
Slates with the Bryograptus shales’ of the same series within the 
Tremadocian would not, I think, be very inconvenient, and the 
boundary between them has never been mapped, while the recognition. 
