94 Birgithe Esmark. 



beginning of collections of land and freshwater Mollusca, and 

 especially made his researches on Tromsøen, which from its 

 rich vegetation and thick woods, is a particularly svitable 

 habitation for snails and slugs. The results have however 

 been as yet very small in species, and cannot give any com- 

 plete idea of what is to be found, but will still have an in- 

 terest for Malakologists, as tending to aid in forming an es- 

 timate of the geographical distribution of the extra-marine 

 Mollusca. 



The Mollusca that have been collected for the muse- 

 um of Tromsø, have been sent to me by Mr. Schneider, for 

 examination. I have also sought to gather information from 

 those who are in possession of shells, and from the works 

 mentioned below. 



As Tromsøen has been most examined and is a wel 

 defined field of research, I shall give the description of thel 

 geological formation of the island, which I take from Mr. 

 Schneiders article in the „Tromsø Museums Aarshefte II, 1879". 



„The most southerly twothirds of Tromsøen consists 

 chiefly of mica-schist with frequent layers of a crystal-grai- 

 ned grey limestone; a fine-grained greenstone frequently crops 

 out, which, especially on the south side of the island goes 

 over to a complétée klo git. Greenstone like formation rich 

 with garnet appear also in the limestone in layers or mas- 

 ses and also a crystalline rock, consisting of hornblende 

 with quartz and feldspar studded with garnet. The most 

 northern portion of the island, north af a line drawn be- 

 tween Sandnæs on the westside and Brevik on the eastside" 

 — and thus to the north of the town of Tromsø — „con- 

 sists chiefly of grey gneis and hornblende-gneis, whill 

 here and there a conspicuous ligth coloured rock consisting 

 of hornblende and a white feldspar projects. 



Limestone is not found in this part of the island. 

 The „Fløifjeld" with „Tromsødalen'' across the sound from 



