Review of Recent Geological Literature. ■>'> 
tionary form and is also given in a series of tables in which the altitudes 
along- each railway line are given with notes showing the amount of cor- 
rection applied and whence it was derived. By means of the latter ta- 
llies the relative accuracy of the altitudes may be determined and new 
data may-be easily incorporated. h. f. b. 
Om Ol&ndftka Ranlcar. By John Gunnar Andersson. (Bihang till 
K. Svenska Vet. Akad. Handlingar, Band 21, Afd. 2, No. 4, : Stock- 
holm, 1895). The author, in the Journal of the Swedish Academy of 
Sciences, gives an account of the formation of drongs, locally called 
•• Rankar," on the shores of the Island of Oland, in which he attributes 
them to marine corrasion during movements of elevation and subsidence 
along the Swedish coast. The formation of these isolated masses of 
rocks depends primarily on vertical joints in the limestone rocks of the 
island. Where a single joint occurs a V-shaped cut in the rock is made 
but where several joints occur a channel with vertical sides is produced 
by the cleaving and breaking up of the layers of rock between the 
joints. He recognizes three stages in the production of a rank or drong 
such as occur on the shores of Oland : First, the weathering and split- 
ting zone, still subject to the action of the sea (Korrasions och 
afspljalkning zonen) : Second, the weathering zone where the action of 
the sea is modified or accelerated by exposure to the action of the air 
(Ablationszonen) : Third, the finished part of the rank, which embraces 
the precipitous sides and flat summit of the drong more or less coated 
with lichens (Stillestandzoneh). 
The article is illustrated with a number of wood cuts and a plate ex 
plauatory of the various processes involved in the formation of the 
drongs. g. k. m. 
Silurisk Posidonomyaskiffer, en egendomlig utbildning af Sk&nes 
Ofoensilur. By Jon. Chi:. Mobekg. (Sveriges Gelogiska Undersok 
ning, Ser. ('. No. L56). Dr. Moberg in this essay describes a 
Posidonomya schist of the uppermost Silurian of Scania in Sweden 
which contains a limited bul interesting fauna. The age is determined 
by three species already described which he finds in it. viz: 
Posidonomya glabra Minister. Beyrichia steuslaffi Krause, and Primitia 
mundula Jones. He considers a new species of Orthoceras which the 
bed contains to be nearly related to o. annulatum Sowerby, and he 
doubtfully identities Beyrichia salteriana Jones, and describes two new 
genera of ostracods, viz : Eoconchoecia and ('<>/j>ns. He also finds two 
new species of Cypridina, one doubtf u'llj referred to this genus. The 
author finds the young of three species of gasteropods and for this and 
other reasons considers the fauna to be pelagic. 
The paper has a plate with excellent figures of the characteristic 
species, and in tlm earlier part of tiie paper the local distribution of the 
schist is described, as well as the nature of the deposits and the general 
character of t he |'a una. <;. i- . \i . 
