xxviii BRITISH GRAPTOLITES. 



with tlie classification, structure, and mode of life of tlie Graptolites, for in these 

 particvdars Scharenberg added very considerably to the oljservations made by 

 Barrande on the subject. 



Classification. — As regards the classification of the Graptolites, he considers 

 that Barrande's suggested division into Monoprion and Diprion is quite inade- 

 quate, for it excludes all the l)ranching forms, such as Gr. f/cDiiiins, Gr. 

 sextans, etc., of the existence of which he himself has no doubt whatsoever. 

 Bronn's (? Richter's) classification into spiral, straight, double-row, and twin- 

 like forms Scharenberg regards as better, but nevertheless not quite satis- 

 factory, as many Graptolites are at first curved and then become straight. As 

 Gladiolites has no distinct axis, and its structure is so peculiar, and withoxit 

 parallel, Scharenberg considers that it should be separated from the Graptolites 

 altogether. 



Structure. — From the structural point of view, Scharenberg's views as to the 

 development of the Biprion forms are of interest. They were antagonistic to 

 those previously held by the majority of graptolithologists, but they have sub- 

 sequently been more or less confirmed by modern research. He points out that in 

 Biprion the cells alternate without exception. " It may be concluded from this 

 that in the development of these animals two cells never arose at the same time, 

 and consequently there is no essential difference between the Graptolites which are 

 distinguished as having one row and those which have two rows of cells." 



As regards the nature of the skeleton of the Graptolites, Scharenberg agrees 

 with Barrande that it was horn-like, and that it possessed a " high degree of 

 flexibility; " but owing to its easy destructibility, Scharenberg, as has been already 

 mentioned, considered that many original characters, such as spines at the cell 

 apertures, etc., were merely the result of decomposition. 



Affinities. — With respect to the afiinities of the Graptolites, Scharenberg held 

 that they were most closely allied to the PennatuliJai. He pointed out, however, 

 as did Prout in the same year, that they differed from the Fennatidiclce in having 

 an external and not an internal skeleton. 



Mode of Grmuth. — Scharenberg strongly criticises Barrande's views as to the 

 mode of groAvth of the Graptolites. He considers that many, especially the 

 branched and double-rowed forms, were fixed in the mud by a kind of " stem," and 

 that consequently the cell apertures opened upwards. If this were the case, then 

 the narrow end, instead of being, as believed by Barrande, the youngest, must be 

 the oldest part, and growth must have proceeded from below upwards. This 

 special mode of growth would indeed be analogous to that in the Pennatiilida', to 

 which the Graptolites are closely related. He also points out, in support of this 

 view, that the narrowness of the polypary does not necessarily imply that the 

 smaller cells are the youngest, for in some species {G. ovatus) the poly])ary narrows 

 at both ends alike. 



