Distribution of the Bhabdopliora. 453 
In a most important note appended to M. G. Linnarsson’s 
paper on the “ Vertical Range of the chief Graptolitic Types 
of Sweden”*, Professor H. A. Nicholson shows that at least 
four of the successive life-groups of Rhabdophora occurring 
in Sweden are now recognizable as characterizing correspond¬ 
ing formations in Britain. 
In his paper on the “Graptolitic Schist of Kongslena”f, 
M. G. Linnarsson makes a successful comparison of the 
faunas of the Lobiferus- and Betiolites-heds of Sweden with 
those of their equivalents in Britain and Bohemia, and points 
out the vital bearing of these new facts upon the doctrine of 
“ Colonies.” 
The geological distribution of the more important genera 
of the Rhabdophora in the live main zones of graptolitic life 
recognized in the most recent memoirs will be found ably 
summarized by Dr. Zittel in his recently published 1 Manual 
of Palgeontology.’ 
Palaeontological. —The palaeontological difficulties are 
also slowly disappearing. In my paper on the “ Improved 
Classification of the Rhabdophora ” J, the majority of the 
known genera were for the first time united into families, in 
the order of what appeared to be their natural relationships. 
The union of Dicellograptus , Hopk., and Dicranograptus , 
Hall, in the single family of the Dicranograptidae, and the 
differentiation of the well-marked families of the Leptograp- 
tidge (Nemagraptidae), Dichograptidge, and Monograptida? 
freed us from much of the prevalent confusion, and served to 
indicate the special lines along which we might expect the 
more important generic distinctions. The provisional arrange¬ 
ment of the diprionidian forms served also to direct special 
attention to many structural points of paramount value in the 
discrimination of homomorphous but distinct species. 
The detailed study of the Rhabdophora of the prolific South- 
Scottish rocks has led to the detection of many fresh criteria 
in the separation of allied species, and has enabled us to cor¬ 
rect at a glance the previously inevitably erroneous specific 
identifications made by our predecessors. The discovery of the 
distinct invariability of many characters formerly regarded as 
varietal, in corresponding forms obtained from England, Ire¬ 
land, and the continent of Europe, has given us a clearer 
insight into the relative value of specific characters, and has 
added largely to our ideas of the abundance and variety of the 
graptolitic species. The careful examination of authenticated 
examples of the species described by early authors lias not 
* Geol. Mag. 1876, p. 245, t Ibid. 1878, p. 278. J Ibid. 1873, p. 555. 
