188 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
At Packerort the most fossiliferous layers are in the upper part of 
the shale, and it might be inferred from this that in the eastern region 
the upper layers had been removed by erosion, but it is equally possible 
that they were never deposited there. 
The characteristic fossils of the Packerort formation are the various 
species of Obolus, chiefly 0. apollinis, in the sandstone, and Dictyonema 
flabelliforme in the shale. Species of other genera of inarticulate 
brachiopods are found in the sandstone, and the shale has furnished 
several species of graptolites which have not yet been satisfactorily 
identified. If Schmidt’s (44, p. 16) figures are to be trusted there may 
be a Didymograptus in this fauna. 
The Obolus or Unguliten sandstone, has, like the Lower Cambrian 
clay of the same region, often been cited as an example of a formation 
which has never been consolidated. At nearly all exposures it is a 
friable sandstone which crumbles readily under the hammer, but in 
certain places it has considerable hardness, and one receives the 
impression that the present condition is due to the removal of the 
cement through leaching. The surface water enters the sandstone 
through joints in the overlying limestone, and being checked in its 
further downward passage by the Cambrian clays, naturally moves 
through the sandy beds. 
Walchow formation. B,and B,, (Glauconitsand and the Glauconit- 
kalk) of Schmidt; B,, Byras Brg, Byry and Bis of Lamansky. 
While the Patient formation is best developed at the extreme 
western end of the Ordovician outcrop, the succeeding formation finds 
its best expression in the east. This, however, is not due to the fact 
that the Walchow formation was deposited in a sea invading from the 
east, for the opposite seems to be the case, but because the upper 
layers have been eroded away at the west, as has already been shown 
by Lamansky (29). The lower members of the formation, the “Glau- 
conitsand”’ and the “ Glauconitkalk”’ are better developed in the west 
than in the east, and the deposits of the same age as the Glauconitkalk 
are still thicker in Sweden. 
On the Walchow and on the Lawa at Wassilkowa this formation 
has five bands easily distinguished on lithological grounds, each with 
its own faunal characteristics. The measurements given here are 
those of the section on the Lawa which presents a more satisfactory 
natural section than any seen on the Walchow. (Plate 4). 
The lowest bed is a soft, easily disintegrated green sandstone, six 
feet in thickness. Upon it rests two or three layers of limestone, 
making a total thickness of six feet, which usually form a bold pro- 
jection from the cliff, being preceded and followed by softer strata. 
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