\cviii BRITISH GRAPTOLITES. 



(Wenloch-Ludlow Series.) 



17. Zone of Gyrtograptus Murchisoni. 



18. Zone of Cyrtograptus Linnarssoni. 



19. Zone of Monograptus testis. 



20. Zone of Monograptus Nilssoni. 



(A table is given showing the Geographical Range of these zones.) 



(9) " The several zones common to two or more regions occupy invariably the 

 same relative position with respect to each other and the same vertical place in 

 the ascending series of formations. Hence we have no choice but to regard them 

 as homotaxially or synchronologically identical." 



(10) " In the face of these results, the host of proofs formerly supposed to be 

 afforded by the abnormalities of the vertical distribution of the Graptolithina, in 

 favour of the doctrines of migration and colonies, vanish. We have at present no 

 evidence to show that any Graptolite group, or even a single species or variety, 

 made its appearance at an earlier date in one region than in another ; and, as a 

 consequence, the place of its origin and the direction of its extension in space are 

 at present equally incapable of recognition. The Graptolite appears to be as 

 restricted in its vertical range, and as Avidely extended in its horizontal distri- 

 bution, as any known form of life hitherto recognised as existent in Palaeozoic 

 times. It is one of the most suitable of fossils for the purposes of the working 

 geologist and systematist ; its short vertical range affording elements for the 

 subdivision of the accepted Lower Palaeozoic formations into their component 

 zones; its wide horizontal distribution allowing of the exact parallelism of 

 synchronous deposits in areas now geographically separated; and its universal 

 dissemination rendering it easy of collection and study." 



I 880 - Three papers by Tullberg appeared in the year 1880. 



I(> ' ;/ ' In the first he describes and figures five new species of 



" Nigra Bidymograp- 7 . . , , „ , n T n , t-, ^ ^ !_ -tr- -i 



** .. JJiaymoqravtus from the Lower Graptolite shales at lviviks- 

 tMS-arter via Kiviks- ° u x 



Esperod," ' Geol. Esperod : I), balticus, D. vacillans, D. pusillus, D. filiformis, 



Foren. Forh.,' bd. 5. and J). SUecicUS. 



I 880 - In a second paper he describes two new genera and 



9' species of Graptolites : (1) Lonchograptus ovatus from the 



,. , „ ,p , Didymog. geminus zone and Janograptus laxatus from the D. 

 Foren. Forh ' bd 5 mucronatas zone at Fagelsang. 



Tullberg's third paper is entirely stratigraphical, and is 



preliminary to his great work — the " Skanes Graptoliter." 



" Laeerfoliden vid -^ e re cogmses several graptolite zones in the Silurian Cyrto- 



Rostanga," ' Geol. graptiis, lletiolites and Lobiferus-ski&er, and also in the beds 



Foren. Forh.,' bd. 5. belonging to the Ordovician. He correlates these with the 



zones previously worked out in Britain by Lapworth. 



1880. 

 Tullberg, 



