242 Dr. G. Linnarsson — Vertical Range of Graptolites in Bweden. 



Dichograptus tenellus, Linrs. It occurs in the uppermost part of 

 the Olenus Schists of Westrogothia, together with SplicBrojpJithalmus 

 alatus, Boeck. The rock which has yielded it corresponds with the 

 Upper Dolgelly of Mr. Belt. 



The Dicti/onema Schists, which occur in Ostrogothia and Scania, 

 abound in Dictyonema JiahelUforme, Eichw., and contain in Scania also 

 a Dichograptus in very great number. Almost the only other fossil 

 found in these schists is a Brachiopod resembling the Oholella Salteri, 

 Holl, from the Malvern Hills, which does not, however, in England 

 occur together with Dictyonema, but in a somewhat lower horizon. 

 The Dictyonema Schists of Ostrogothia in all respects agree with 

 the bituminous schists which in the Baltic provinces of Russia 

 overlie the " Ungulite Grit." In certain localities in Scania, Dicty- 

 onema seems also to occur in the uppermost part of the Olenus beds, 

 and there a transition might thus take place between the Olenus 

 Schists and the Dictyonema Schists, while in Ostrogothia they seem 

 to be sharply defined. 



From the Cer atopy ge limestone not a single Graptolite is known, 

 though it contains intercalated bands of schists. In the overlying 

 Lower Graptolitic Schists they occur, on the contrary, very plenti- 

 fully. The fauna of these schists is quite analogous to that of the 

 Skiddaw and Quebec groups, but hitherto a far less number of 

 generic types has been found in Sweden than in England and 

 Canada. The most common genera are Phyllograptus and Didymo- 

 graptus. The former is the most characteristic, and therefore the Lower 

 Graptolitic Schists might also be termed '' Phyllograptus Schists." 

 Didymograptus is represented by several species, but in some localities 

 is comparatively rare. Besides the above, there are not with certainty 

 known any more genera than Tetragraptus and Dichograptus. There 

 is also an extremely slender branched form, of which I have not been 

 able to make out the generic characters ; but perhaps it belongs to 

 Pleurograptus. In one single locality, at Eajelsang in Scania, I have, 

 together with forms characteristic of the Lower Graptolitic Schists, 

 such as Phyllograptus and Didymograptus hirundo, found numerous 

 specimens of a Climacograptus, a genus which elsewhere in Sweden is 

 found only at higher horizons. The stratigraphical relations of the 

 schists containing this mixed fauna have not yet been made out. In 

 petrographical as well as in palaeontological respects they differ from 

 the true and undoubted Lower Graptolitic Schists found at other 

 places in Scania, which, as those of Westrogothia and Jemtland, have 

 yielded no traces of Diplograpti or Climacograpti. I have guessed 

 that the schists in question might possibly be intercalated in the 

 Orthoceras Limestone. In Norway the Orthoceras Limestone contains 

 intercalated bands of schists, but of their faunae nothing is known. 

 Some authors have referred the Skiddaw and Quebec groups to the 

 Primordial Zone. That view must, however, be abandoned, as those 

 groups are evidently equivalent to the Swedish Lower Graptolitic 

 Schists, which repose on a bed — the Ceratopyge Limestone — the 

 fauna of which has a decidedly Lower Silurian character. 



In the Orthoceras Limestone Graptolites are extremely rare. I 



