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This fossil is rarely but regularly found in Oeland, in the lower- 
most, glauconitic Asaphus-limestone, in Russia in the three divisions 
of the zone Bij: (Bur, Bur, and Bi) of LAMANsKY. On the basis of 
his investigations Lamansky parallels the lower half of By, with the 
Lower Asaphus limestone of Oeland, but the Strophomena-Jentzschi- 
conglomerate with the Upper Asaphus-limestone and the Gigas-limestone 
of Oeland, and with the upper part of LAMANsKY’s zÔne Bir, and 
with his zône Bru, of Russia, so that from this it follows, that 
Strophomena Jentzschi Gag. is spread over a larger vertical extent 
than ANDERSSON could have surmised at first. In South-Norway the 
fossil has been found in the zône 3 ec. 
If, therefore, we wish to parallel this erratic block with any of 
the Lower Silurian strata, it is necessary, in view of the varying 
petrographical character of the divisions, which deserve consideration, 
and in view of the different character of each of them in different 
regions, to find out from which region the boulder most probably 
originates. 
According to Linpstrém (11 p. 9—12) Asaphus raniceps Dalm. 
occurs already in the Lower Gray Orthoceras-limestone of Sweden 
and is still found in the Upper Gray Orthoceras-limestone. 
According to Scumipt this species is observed in Russia in the 
zones B 2b—B 36; according to Lamansky (22 p. 169) in the upper 
strata of the zone By, up to the lower strata of Bur: 
Brécerr asserts that it is not quite certain whether they are met 
with in Norway (5 p. 92). 
Most probably this erratie bloek does not originate from the 
mainland of Scandinavia, Strophomena Jentzschi Gag being known 
there only in South Norway. Moreover the rocks from those zônes 
differ from our boulder. . 
Likewise the Russian Silurian need not be considered although 
the latter fossil also occurs in Russia. It bas not been observed yet 
to the west of Reval. In that region only Bui, of the zone B 
exists and this division consists of calcareous sandstone. Our boulder, 
therefore cannot come from the East-Baiticum. 
As has been said, only one erratic block with Strophomena Jentzschi 
Gag. from the North-Balticum is known. The petrographical character 
of it does not agree with this specimen. Boulders of grey limestone 
have been found there, indeed, which belong to the Asaphus-lime- 
stone of Wiman and may therefore be of the same age. 
In Oeland the Lower Asaphus-limestone consists of limestone partly 
containing glauconite and partly free from that mineral of which 
