206 On the Distribution of the Rhabdophora. 



geographically continuous, but now more or less broken up 

 into isolated fragments. That the zones missing from the 

 Lower Palaeozoic series as developed in any single region owe 

 their apparent absence generally to the fact that the strata 

 have as yet been imperfectly studied, will be evident on a 

 comparison of the Scanian column with the succession of 

 zones as developed in Britain. The zeal and acumen of the 

 Swedish geologists in the study of the Scanian rocks have 

 resulted not only in the detection of all the Graptolite zones 

 already recognized amongst us in that region, but in the dis- 

 covery of several others, of the existence of which we were 

 previously unaware. That the half-dozen zones recognizable 

 upon the opposite side of the Atlantic were originally con- 

 tinuous with their British prototypes is not at all probable ; 

 but, judging from their correspondent position in the. succession 

 of formations, it may be asserted with confidence that, from a 

 geological point of view, they answer to their representatives 

 on this side of the Atlantic, not only in fossils but in the 

 special epoch during which they were deposited. 



(x.) In the face of these results the host of proofs formerly 

 supposed to bo afforded by the abnormalities of the vertical 

 distribution of the Graptolithina, in favour of the doctrines of 

 migration and colonies, vanish into thin air. These apparent 

 evidences are now seen to have been fallacious appearances, 

 due simply to defective knowledge. In every case where the 

 subject is capable of proof, we have shown that the facies of 

 the Graptolite fauna in every subformation was identical all 

 over the Lower-Palaeozoic world. We have at present no 

 evidence whatever to show that any single 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 conse- 

 quence, the place of its origin and the direction of its exten- 

 sion in space are at present equally incapable of recognition. 



The consideration of the bearing of these results upon the 

 study of the morphological development of the Graptolites 

 themselves demands some notice ; but the subject is to a cer- 

 tain extent foreign to the main object of the present paper. 

 It is enough to have demonstrated that the Graptolite appears 

 to be as restricted in its vertical range, and as widely extended 

 in its horizontal distribution, as any known form of life hitherto 

 recognized as existent in Palaeozoic times. Of all fossils it is 

 the most frequent and the most widely disseminated in the 

 rocks of that age. It is found certainly in the greatest abun- 

 dance in the more carbonaceous deposits in the deeper water 

 beds, but it is present more or less in all sediments. This is 

 probably owing to the fact that at one stage or other of its 



