xxii BRITISH GRAPTOLITES. 



forms wliicli A^'ore then new to science : — (o) Or. Nilssoni; (1) Or. colonus ; (5) Qr. 

 bohemicus; ((>) dr. Eoemeri; (7) Or. turriculatus ; (S) Or. Becki ; (*>) Or. 

 proteus; (1(») Or. Halli; (11) Or. testis; (12) Or. palmeus, var. lata and var. tenuis; 

 (13) Or. ovatus ; (14) (/;■. chimaera ; (15) BaMritcs fugax; (IG) E. peregrinus ; 

 and (17) 7i'. gemmatus. Little or no donbt is left as to the specific cliaracteristics 

 of most of these forms, and they are easily recognisal)le from Barrande's descrip- 

 tions and figures. 



In the description of his (18) Or. tectus and (19) Or. nuntius, Barrande enters 

 into a lengthy explanation of the various aspects that the cellules may assume 

 according to the direction of compression. Thus he shows that specimens of 

 Graptolites apparently biserial may really be the compressed scalariform views of a 

 uniserial form. Here, however, Barrande's inference, correct as it was respecting 

 Graptolites in general, led him occasionally astray, and he erroneously described a 

 true biserial species, viz. his Or. tertiu^, as a uniserial form. 



Barrande described the structure of his remarkable new genus, Oladiolitr.s 

 (or Beliolites), and its type species (20) 0. Geinitzianus, with special care 

 and accuracy of detail. The median filiform axis visiljle in some specimens he 

 holds to be part of the external network, and not to represent a division 

 between the two series of cellules, for it is often discontinuous. As regards the test 

 of Retwlites, Barrande considers it is very improbable that it was continuous as in 

 other Graptolites, but the network might, perhaps, have been covered by a thin film. 



Barrande's brilliant memoir acted as a great incentive to the stndy of indi- 

 vidual G rapt elite species, and since its pul^lication papers on this subject have 

 been numerous. His clear presentation of the different specific criteria trained 

 the eyes of those who immediately followed him, and for the next twenty to 

 twenty-five years research was mainly in the direction • of the collection and 

 description of new species ; and side by side with this some important additions 

 were made to our knowledge of the structure, mode of life, and zoological position 

 of the Graptolites. The detailed study of their geological distril)ution was, however, 

 somewhat neglected, and was not taken up until a much later date. This was, no 

 doubt, owing largely to the fact that graptolithologists, fascinated by the brilliance 

 of Barrande as a paleontologist, naturally accepted also his ideas with respect to 

 migration and colonies, unaware that stratigraphy in the Lower Palaeozoic rocks 

 had not yet advanced to that degree of detail by means of Avhicli it was possible 

 to interpret correctly the complexities of the Bohemian succession. 



In 1850 Verneuil noted the occurrence of Or. colonvs and 

 '^^- Or. testis in the Ampelite schists of Neuvilette (Brittany). 



<-r>n c r^'' ^ . Tlicsc arc iucluded iu liis " sccond fossillfcrous stagc." In his 

 ' Bull. Soc. Geol. dc _ - 



Fraiifo,' vol. vii, " third fossiliferous stage," the representative of the Upper 



Silurian, he records Or. jrriodon as being the most common 

 species. 



