xl BRITISH GRAPTOLITES. 



not specifically recognisable. But while his figures do not admit of the recognition 



of the individual species, the general habit is fairly well given, and it is evident 



that nearly all the forms are of Wenlock age. 



In the same year Salter described a new genus of Grapto- 



lite, which he called Graptopora, and he considered this to be 

 Salter, . . _. . _ __. 



A c . intermediate m character between a Graptolite and a rene- 



Assoc. or Amer. L 



Naturalists, Montreal, stella. The species which he regarded as typical of the 

 genus was his own Graptopora (Fenestella) socialis. This 

 genus had already been described by Hall under the title of Bictyonema. 



In a paper entitled " Notes upon the Genus Gh~aptolithus," 



1858-9 • • 



in 1859 — a part of which paper had been communicated to 



"Notes upon the Genus Sir WiUiam Lo g an in 185 ? C Report of Progress, Geol. 



Graptolithus and a Survey of Canada '), — Hall criticises to some extent the views 



description of some expressed by Barrande in his ' Graptolites de Boheme,' and 



new forms from the })j tl ier - European graptolithologists. It is interesting to 



Hudson River Group," note ^ th t neatest palaeontologists of that day, living 

 ' 12th Report on the . . ., ° . . f . . _° „ ,.«. 



St t O 1 ' t All ' on °PP 0S1 t e sides of the Atlantic, had totally different grapto- 



litic material to work upon. Hall's examples of Graptolites 

 were practically all branching forms from Lower Silurian (Ordovician beds), while 

 Barrande' s were all simple forms of Upper Silurian age. This was a disadvantage 

 to them in the interpretation of their results at the time, but it was nevertheless 

 extremely fortunate for the progress of science, for owing to this circumstance 

 both the Lower and Upper Silurian Graptolitic faunas were worked out inde- 

 pendently by these two great palaeontologists, neither being biassed by the views 

 of the other. 



Hall was unwilling to accept the European genera, Monograpsus, Diplograpsus, 

 and Gladograpsus, believing that there was not sufficient reason at that time for 

 separating branching forms from the unbraiiched, and regarding all those with a 

 single series of serratures as having been originally composed of two, four, or more 

 branches. He also rejects Geinitz's genus Nereograpsus. He states that the 

 Canadian specimens "sustain the opinion already expressed that Bictyonema will 

 form a new genus of Graptolites, the serratures being on the inner side;" while as 

 regards the form of the polypary in this genus, he concludes that while its mode of 

 growth was "probably flabelliform in some species, it is clearly funnel-shaped in 

 l>. retiformis." 



Alanv new species are described by Hall in this work and partly figured, the 

 majority being grouped under the single generic name of Graptolithus. These 

 embrace (I) Gr. logani and (2) Gr. abnormis (now placed in the genus Logano- 

 graptus), and (3) Gr. flexilis (Glonograptus). Hall's specimens of Loganograptus 

 Logani show the presence of a disc for the first time in the history of graptolitic 

 research. 



