233 
from the Gotland species and resembles Pholidops antiqua Schloth. 
It is not known as yet which of these two fossils occur in Oesel 
and in Estland. 
Beyrichia Jonesii Boll. has been reported by Kirsow (13 p. 13 pl. 
II fig. 10—12) of Gotland from LiNDpsrRÖM’s zÔnes c—h, by VAN 
HoePeN (l.c. p.132) from his zône s®‚. At Schonen this fossil has not 
been found, and nothing is known of it in Oesel and Estland. 
Proetus concinnus Dalm. is mentioned only by Scamrpr (I. c. p. 44) 
from the Lower Oesel stratum (zône J) of the Russian Baltic provinces, 
of Gotland by Linpstrém (12 p. 3) from the zônes c—e, and by Van 
HoePeN from his zÔne y (near Mulde) (1. e. p. 142). Moreover this fossil 
has been found with Beyrichia Jones Boll in boulders, associated 
with Leperditia Baltica Kichw. and Beyrichia spinigera Boll. (2 p. 
au, Lf p.. 902). 
I, therefore, feel justified in assuming, that this boulder probably 
agrees as to its age, with the Lower Oesel stratum of the Russian 
Baltic provinces. 
In Oesel the Lower Oesel stratum consists almost entirely of blue 
marl and dolomite. Limestone occurs only in the West of the 
peninsula Taggamois (+ p. 46). The equivalent layers in Gotland, 
on the other hand, are composed of marl, marly limestone and 
limestone, and the equivalent layers on the mainland of Sweden of 
grapholite-shale, so that this region cannot be considered as the place 
of origin. 
Gotland and the part of the Baltic between this island and Oesel 
and of these probably, first of all, the island of Gotland together 
with its approximate vicinity is, therefore, in all likelihood to be 
looked upon as the locality from which our erratic block was derived. 
Delft, May 1919. 
REFERENCES. 
1. Davinson, Tu. 1864—1871. “British Fossil Brachiopoda. Vol. III: Devonian 
and Silurian Species.” Londen. 
2. Krause, A. 1877. “Die Fauna der sogen. Beyrichien- oder Chonetenkalke des 
norddeutschen Diluviums.” Zeitschr. d. d. geol. Ges. Bd. XXIX, S. 1—48. 
3. AnceLin, N. P. 1878. “Palaeontclogia Scandinavica. Pars I.’ Stockholm. 
4. Scumipt, F. 1881. “Revision der ostbaltischen silurischen Trilobiten, nebst 
geognostischer Uebersicht des ostbaltischen Silurgebietes. Abt. 1” Mém. d. l'Acad. 
Imp. d. Se. de St. Pétersbourg, 7e Ser., T. XXX, No. 1. 
5. Broéeeer, W. C. 1882. “Die silurischen Etagen 2 und 3 im Kristianiagebiet 
und auf Eker etc.” Kristiania. 
6. Kiesow, J. 1884. “Ueber silurische und devonische Geschiebe Westpreussens.”’ 
Sonderabdr. Schr. d. naturf. Gesellschaft in Danzig, N F., Bd. VI, S. 205 —303. 
