395 
bergen during tlie Norwegian North-Atlantic Expedition 
1876—78. and tliat shells as Portlandia arctica, Porilandia inter- 
media, Cardium groenlandicum, Cardium ciliatum, Astarte horealis, 
Astarte hanksi, Tellina calcarea, Saxicava aretica, and Cyrtodaria 
siliqua have been dredgedjat depths from ca. 500 to ca. 1350 fms. 
bctween Jan Mayen and Iceland during the Danisli Ingolf- 
Expedition 1895—96. Kecently Mr. E. Hagg, fil. cand., bas 
kindly informed me that the SwedisbNorth Polar Expedition 
of 190 0 also dredged several shallow-water shells, but not many 
speciniens, at great depths between Jan Mayen and Spitzbergen. 
AVhile Friele (1. c. 1879) explains this phenomenou by the 
theory of transportation by floating ice, Professor W. Brøgger 
(1. c. 1900—1901), and A. S. Jensen (1. c. 1900), have on the 
contrary urged that a sinkiug of the sea-bed more probably has 
taken place than a transportation of the shells, and Professor Fr. 
Nansen has arrived at the same conclusion ^). 
If the phenomenon be accounted for by the hypothesis of a 
sinking of the seabed, Prof. Brøgger has concluded that the sea- 
bottom of the North Polar Basin, during the time of the greatest 
ice-sheet of Europe, must have been uplifted to a height surpassing 
by 2600 metres that of the present time. 
Let us, however, consider the reasons which the named authors 
urge against the explanation of the phenomenon by the theory of 
transportation by floating ice. The reasons are as follows: 
1) Among the dead shells which occur at considerable depths in 
the North Polar Basin are those of Portlandia intermedia, (Dead 
shells are found at depths of 658, 1003 and 1309 fms.). The 
vertical distribution of this species in the North Polar Basin 
reach from 40 to ca. 500 fms. As it does not occur at lesser 
depths than at 40 fms., it is outside the reach of the ice. 
A. S. Jensen writes about this form^): „Af denne lille Musling 
M Letter to Brogger. 1. c. p. 94—96. 
y) A. S. Jensen, 1. c. 1900. p. 232. 
