STUDY OF THE GRAPTOLITES. 271 



In the figure of C. linearis given in the Intellectual Observer, the divisions 

 are shown as originating from one side only, while the main axis is 

 continued, but not to our view branching and rebranching as described ; 

 not at least in the sense in which we apply that term to such forms as 

 G.flexilis of this paper, or to such forms as Dendrograptus. There is 

 no division of the celluliferous parts of the stipe, if we may judge from 

 analogy with similar forms in the American rocks. 



Should the term Cladograptus of Geinitz be retained for certain forms, 

 as suggested above, then the Genus Cladograptus of Carruthers must 

 be abandoned; and in any event it can scarcely be continued, since the 

 same generic term had been previously applied to other forms of grapto- 

 lites, and, as now appears, with as much reason for its adoption as the 

 term Didymograptus, which cannot properly be so extended as to include 

 all the species originally named under it. 



I have little doubt that the forms to which Mr. Carruthers has applied 

 the name Cladograptus are similar to our G. (/racilis and G. diver gens, to 

 to which I have applied the name Ccenograptus ; and it may be a ques- 

 tion whether the Nemagraptus of Emmons, proposed in 1855, is not of 

 the same character ; though the remarks of that author concerning the 

 cellules would, if verified, exclude the typical species from that group. 



The discussion in regard to nomenclature is at this time of small con- 

 sequence, compared with that of the structure ; and, on this account, 

 these forms require to be separated from Graptolithus proper. 



The question as to the limitation of the term Graptolithus still remains 

 a matter for discussion. I have, on page 170, repeated what I had previ- 

 ously written upon this subject, and I still find little reason for a modifi- 

 cation of those views. Mr. Carruthers, speaking of the compound forms 

 so common in our rocks, remarks : " Whether or not all the American 

 graptolites are fragments of this more complex form, I cannot say ; but 

 it is certain that few if any of the European species could belong to it. 

 In many species the termination of both the extremities of the polypary 

 is known, and that end which should be united to the compound group is 

 certainly free." This might have been said of our own species in past 

 time ; but experience has proved it otherwise, and at this time we have 

 but one form of the monoprionidian type which we suspect to have grown 

 in single stipes. But if this be true of European species, they have been 

 erroneously represented. Even taking Mr. Carruthers' own figures of 

 " two perfect specimens of G. clingani" we are scarcely willing to accept 

 the assertion. If we examine all the figures of Portlock, we shall find 



