THE 



GEOLOGICAL MAGA.ZINE. 



NEW SERIES. DECADE II. VOL. III. 



No. VI.— JUNE, 1876. 



I. — On the Vertical Kange of the Graptolitio Types in 



Sweden. 



By Dr. G. Linnarsson, 

 Director of the Geological Survey of Sweden. 



OF the Swedish Graptolites up to this day but very little seems to 

 be known in foreign countries. They merit, however, more 

 attention than has hitherto been bestowed on them — chiefly perhaps 

 because of the scantiness of the literature. The Graptolitic faunae of 

 Sweden have many analogies to those of other Silurian districts, and 

 are therefore of great importance for the identification of the strata. 

 An acquaintance with them is also required if one wishes to obtain a 

 somewhat accurate knowledge of the vertical and horizontal range 

 of the various types. A short account of them might therefore jjos- 

 sibly have some interest even to an English geologist. 



In Sweden it is chiefly at four horizons that the Graptolites are 

 numerous and predominant, but also at many others some single 

 species are found. In general the Graptolitic faunge in Sweden are 

 more separate and unmingled than in England, certain forms which 

 in England have a wide vertical range being in Sweden restricted to 

 one horizon. 



The Cambrian and Silurian deposits of Sweden can be arranged in 

 the following manner, in descending order : — 



1. Uncrinurus Beds. 



2. Leptcena Limestone. 



3. Upper Graptolitic Schists. 



4. Brachiopod Schists. 



5. Trinucleiis Schists. 



6. Chasmops Limestone. 



7. Middle Graptolitic Schists. 



8. Orthoceras Limestone. 



9. Lower Graj^tolitic Schists. 



10. Ger atopy ge Limestone. 



11. Dictyonema Schists. 



12. Olemcs Schists. 



13. Faradoxides Schists. 



14. Fucoid Sandstone. 



15. Eophyton Sandstone. 



The Sandstones — which lie unconformably on the fundamental 

 gneiss, and are overlain by the " Primordial Zone," thus agreeing in 

 position with the English " Longmynd Group " — have not yielded 

 any Graptolites, if we except a single, very faint, impression found 

 in the shale accompanying the Eophyton Sandstone, which represents 

 a Dictyonema or something allied to that genus. I am, however, very 

 uncertain of the true nature of this impression ; it is possible that it 

 is not even of organic origin. 



In the Faradoxides beds, I have myself seen no traces of Grapto- 

 lites, nor have any been found by other observers. 



The oldest Graptolite hitherto described from Sweden is the 



DECADE II.— VOL. III. — NO. YI. 16 



