Dt\ G. Linnarsson — Vertical Range of Graptolites in Sweden. 243 



have only found a very few fragments of Pliyllograpti in Dalecarlia 

 and Jemtland. No doubt the physical conditions prevailing in the 

 sea when this limestone was formed were unfavourable for the 

 existence of Graptolites. 



Immediately above the Ortlioceras Limestone there is a series of 

 mostly black schists, which are known almost only from Scania, 

 though they occur also in Jemtland ; in the middle provinces of 

 Sweden they are entirely wanting. By Angelin and other writers 

 they have not been distinguished from the other graptolitiferous 

 rocks situated above the Orthoeeras Limestone, but they contain, 

 undoubtedly, a peculiar fauna, and occupy a much lower horizon 

 than the Upper Graptolitic Schists. I have therefore proposed to 

 name them Middle Graptolitic Schists. Though their stratigraphical 

 and palgeontological relations were misunderstood, the Middle Grap- 

 tolitic Schists have long been known. At an early period Hisinger 

 described from this horizon CUmacograptus teretiusculus and Didy- 

 mograptus geminus {=.D. MurcMsoni, Beck.). Of other genera Dicel- 

 lograptus ^ and Dicranograptus are the most characteristic, though 

 Diplograptus occurs far more plentifully. These schists could there- 

 fore be termed Dicranograptus Schists. Of the genera Graptolithus 

 and Bastrites I have not found any representatives in them, with 

 the possible exception of one single fragment of Bastrites, found in 

 a loose slab seeming to belong to this horizon. The Middle Grap- 

 tolitic Schists occur also in Norway, where they form the uppermost 

 part of Stage 3 of Professor Kjerulf, and in the Isle of Bornholm, 

 whence some species were long ago described by Geinitz, and where 

 their stratigraphical relations have lately been worked out by 

 Professor Johnstrup. In Britain they have their nearest analogue 

 in the Moffat series,^ 



In the Chasmops Limestone Graptolites are rare, though not quite 

 so much so as in the Ortlioceras Limestone. I have only found 

 species of Diplograptus and perhaps of Climacograptus. 



The Trinucleus Schists are also in general poor in Graptolites, but 

 they have usually been confounded with the Upper and Middle 

 Graptolitic Schists, and therefore, erroneously, stated to contain very 

 numerous species of that group. The few species occurring in the 

 Trinucleus Schists are almost exclusively confined to the lower beds, 

 whicli are usually blackish, and petrographically resemble some 

 varieties of the Upper Graptolitic Schists. From that horizon 

 Hisinger described the Diplograptus pristis. Of other genera I 

 have only found Dicellograptus. In the upper beds, which are 



^ Though I do not think that Mr. Hopkinson has correctly interpreted the 

 structure of the species referred by him to the genus Dicellograptus, they seem to 

 form a very natural and well-detined group. 



2 I should, however, think that the Motfat series, as defined by English geologists, 

 includes also beds equivalent to the lower portion of the Swedish Upper Graptolitic 

 Schists, which is characterized by Rastrites peregrinus, Graptolithus lobifet\ and 

 Sagittarius, Climacogmptux teretiusculus and Diplograptus palmeus, while in the 

 upper portion Gi-aptolithus priodon and Urtiolites Geinitziaizus are the prevailing 

 species. [Mr Charles Lapworth has shown that the Moffat series is divisible into 

 distinct groups, characterized by distinct species of Graptolites. — H.A.N.] 



