Pupa ( Vertigo ) arctica Wallen, in Iceland. 243: 
north (Quickjock, Pitea, Herjadalen. etc.) to Orebro, Stock- 
holm. Nykobing (Sodermanland), spread in the North Wester- 
gotland, and at Jonkobing. In Finland it is spread over most 
of the country, and the species has certainly a large distribu- 
tion in Northern Russia and Siberia (var. extima West from 
Baklanowsky). Moreover this species is found in Tegel. at 
Berlin, Ivleinen Schneegrube in Riesengebirge (by Professor 
Reinhardt), Rotlerberg opposite Peitler Ivofel in Tyrol, and 
in Tatra. In the fossil form it is found by Odhnerf, in Bil— 
lingen in Westergotland (Sweden). What Geyer writes^ on 
the occurrence of Pupa arctica and other arctic species is of 
great interest ; he says : ‘ During the diluvial period 
the large extension of glaciers took place and with it a 
period which still is manifesting itself in the molluscan world. 
The tropical climate of the tertiary period gave way to a 
colder one and at the end of it, the Alps had no glacier 
Pupa ( Vertigo ) arctica. 
1000 m. higher up than now-a-days. When the temperature 
sank 4 0 Celsius under the present temperature, the glaciers 
spread down the valleys and over the lower country, and from 
the north they stretched as far as the German Mittelge- 
birge. The breadth of that zone, which was free from ice 
was about 300 km., having the character of tundras with 
their abundance of brooks, moors and streams of water divided 
by large and small forests. Formerly the more northern 
regions and the high mountains had their own fauna character- 
istic of a cold climate, but when forced by the advancing glacier 
it was compelled to move southward, and from the Alps into 
the ice-free ‘ sack,’ and here came a mixed fauna, where arctic, 
alpine and aboriginal elements mingled together. Its char- 
acter was mainly arctic-alpine. The incontestible retrograde 
movement of the glaciers at the end of the ice-period to the 
arctic zones and to the tops of the Alps, and the co-existent 
warmer climate in the lower country, had the effect that the 
t Die Entwickelung der Molluskenfauna in dem Kalktuffe bei Skultorp in 
Westerg-otland, in Geol. Forh. , Stockholm, 1910. 
J Die Weichtiere Deutschlands, Stuttgart, pp. 104-106. 
1914 Aug. 1. 
