KONGL. SV. VET. AKADEMIENS HANDL. BAND. 19. N:0 6. 33 



It must have been in some sheltered bights, where a calcareous mud found stillness 

 enough to allow it to settle down, that such deposits as the fine grained liraestone of 

 Sandarfve, or Samsugn with their numerous and beautifully preserved shells originated. 



In general the shells werc middle sized, only a few, as Pleurotomaria valida, 

 or Pl. cirrhosa attaining a greater size. Fragments of an undeterminable shell from 

 the shale of Gnisvärd attain in the height of the body whorl alone 82 mm. and in 

 breadth 98 mm., this being the largest fossil shell, known in Gotland. This size and 

 the comparative rarity of tiny shells also militate against any assumption of great 

 depth for tliese forms, as only small sized species have been dredged up from the 

 abyssal depths. 



2. The fauna had a tropical character. In consideration of the great numbers 

 of Pleurotomarias, Trochi, Turbinidse and the large Pteropods the assumption of a 

 tropical character of the fauna may seem justifiable. 



Older descriptions of Gotland Gastropoda. 



There has been no want of workers in this field, as we can learn by a review 

 of the mevnoirs of the authors previous to this. The first time any mention has been 

 made in print of the Silurian Gastropoda of Gotland was when Magnus von Bromell 

 published the »Articulus secundus» of his »Lithographia Svecana» '). He there, pages 

 28 — 37, enumerates and summarily describes 21 different numbers of fossil Gotland 

 Gastropoda. But as both the descriptions and the ligures are very unsatisfactory — 

 the originals being raostly mere nuclei — I have not been enabled with any degree of 

 certainty to identify more than a few. Thus N:o 5, page 30, and N:o 6, p. 31, in all 

 probability are specimens of Pleurotomaria alata. N:o 21, p. 36, is an Oriostoma and 

 probably Oriostoma sculptum Sow. In N:os 26 — 27 we see nuclei of Murchisonias and 

 N:o 27 may be M. attenuata. 



LiNN^us has left no descriptions of any fossil Gotland Gastropoda. In the relation 

 of his travel on Gotland in 1741 he only mentions them in passing. On page 189 he 

 says: »Petrilicata plåckades af oss hela timarna på wästra Stranden (af Kapellshamn), 

 ibland hwilka woro ganska många Conchita; striatas och Cochlitie» .... i. e. »Petrifica- 

 tions were collected by us for several hours on the western shore, amongst which 

 were a great nuraber of Conchitai striata3 and CochlitsR» . . . 



Wilhelm Hisinger began his long, honourable and meritorious activity as the ex- 

 plorer of the geology and palffiontology of Sweden so long back as in 1789 at the early 

 age of 23 years with his first memoir and in 1798^) he published »Minerographiske 

 anmärkningar öfver Gottland». On page 286 he enumerates with other fossils only a single 

 y>Turl)o? i pisolit kalksten». In 1808 »Samling till en mineralogisk Geografi öfver Sverige» 

 was published and there he only recapitulates the remarks in the preceding paper. The 

 number of Gastropoda accepted by Hisinger was raised to ten in his geological de- 



') III the »Acta Literaria et Scientiarum Svecire», Vol. III, Upsnlu 1738. 

 ■') In the Transactions of the K. Sweilish Ac. of Sciences. 



K. Vet. Akad. Handl. Band 19, N:o ft. 5 



