TWENHOFEL: EXPEDITION TO THE BALTIC PROVINCES. 319 
west of the village and railroad station, Tamsal. The rock is there 
quarried for lime, an extensive plant being in operation. This is 
taken as the type-locality of the zone, since Schmidt gives none, as 
well as the type of the formation. About twelve feet of strata are 
visible here, the basal two feet belonging to the Jérden beds and the 
upper ten feet to the Borealis banks. 
The rock is a gray and yellowish gray Pentamerus borealis breccia. 
No two valves were seen together and little else can be seen. Clath- 
rodictyon is the only other common fossil. 
The rock at the Weissenfeld locality previously described (p. 317) 
is not so exclusively composed of Pentamerus borealis, and entire shells 
are not uncommon. At Helterma, on the island of Dago, the beds 
outcrop on the beach and, as at Weissenfeld, the rock is not so com- 
pletely a mass of Pentamerus, although parts are fully as much so. 
Syringophyllum organum, Clathrodictyon vesiculosum and other corals 
are not uncommon here. This outcrop may represent the upper 
portion of the division. The Borealis banks are also shown by eight 
or nine feet in the Podrang quarry near Tamsal, and there the shells 
do not make such a great proportion of the beds. 
From the localities cited it appears probable that only the lower 
portions of this zone have been seen, unless the exposures at Helterma 
lie above the base. Schmidt was inclined to believe that the Borealis 
banks lose their character as a unit upon the island of Dago, reaching 
this opinion from finding P. borealis in the Jérden beds at Kallasto. 
This is by no means certain, as this shell also occurs in the Jérden beds 
at Tamsal, and in some places it should be more abundant than else- 
where in this basal division, and perhaps this is the case at Kallasto. 
As a shell breccia, the division probably has only a local development. 
The fauna of this division has never been carefully studied. It is 
probably not large, since the conditions of fossilization were not such 
as to lend themselves to the preservation of delicate forms. The 
omnipresent fossil is Pentamerus borealis. Syringophyllum organum, 
Favosites gothlandicus, Clathrodictyon vesiculosum, and small bryozoans 
occur more or less rarely. 
(c) Ratkiill beds. This division is the thickest of the three belong- 
ing to this formation, Schmidt stating that 100 feet may be present. 
It appears to be continuous with the Borealis banks, and receives its 
name from Raikiill, the estate of Count Keyserling. In general, the 
rock is a coralline limestone, in some places completely dolomitized, 
in others a mass of corals, and in still others well-bedded crystalline 
limestone. The division makes its appearance about twenty miles 
