xii BRITISH GRAPTOLITES. 



subdivision of tlie forms tlien included under the genus 



"■ Graptolithus. He divides tliem into (a) straiglit, and (h) 



^ . \'^ spirally curved forms. In the first group (a) he places (1) Gr. 



' Gnmdriss der Vor- i J o i v / r v / 



steinerungskimde.' foUaceus, (2) Gr. pvistis, (3) Gr. folium, (4) Gr. dentatus, 



(5) Gr. priodon, (6) Gr. ludensis (with its variety Gr. virgu- 



latus), (7) Gr. teretiuscidus (this he regards as synonymous with Gr. j^riodon and 



Gr. Sagittarius;), (8) Gr. Sagittarius (which he believes to be identical with Gr. 



scalaris), and (9) Gr. serratus. He refers to the two branched forms, Gr. 



geminus and Gr. Murchisoni, and suggests with considerable hesitation that they 



may be identical with Gr. Sagittarius and Gr. priodon respectively. In the second 



group (h) he places only one species, Gr. convolutus. He figures a few of these 



species, but some of his figures are merely copies of those of previous authors. His 



figure of Gr. foliaceus clearly represents an example of Betiolites Geinitzianus, and 



the network is well shown. He retains unmodified his previous views as to the 



structure and affinities of the Graptolites (op. cit. ante, 1842). 



In 1847 Hall described in his " Graptolites of the Inferior 

 1847. 

 „ ' Strata of the New York System " a number of forms of Grap- 



" Graptolites of the tolites from the Utica slate and the beds of the Hudson River 



Inferior Strata of the group. The species described and figured include five forms 



New York System," identified by him with forms described or noticed by previous 



' Palaeontology of New authors, and eight additional species for which new names are 



proposed. It is very doubtful if any of the forms referred 



by Hall to species previously described are identical with those species. Thus his 



(1) Gr. Jurist is (His.) is not Hisinger's form of that name; (2) Gr. scalaris, Linn., 



is mainly Climacograptus hicornis, Hall; (3) Gr. secalinus, Eaton, is an ally of 



Diplograptus foliaceus, Murch., deformed by cleavage; (4) Gr. Sagittarius (His.) is 



almost certainly an example of Didymograptus, as is also (5) Gr. tenuis (Portlock). 



The new species described and named by Hall include (()) Gr. sextans, (7) Gr. 



furcatus, (8) Gr. ramosus, (9) Gr. serratulus, (10) Gr. bicornis, (11) Gr. 



mucronatus, (12) Gr. gracilis, and (13) Gr. Isevis. This last is not a- Graptolite, 



but an alga or a worm track. All the figures are good, and nearly all the species 



are recognisable. 



Hall at that time grouped all these Graptolites under the single title Grapto- 

 lithus, which was the only genus then recognised, but several of them have 

 subsequently been made the types of distinct genera. Thus the forms there 

 described as Gr. hicornis, Gr. ramosus, Gr. sextans, and Gr. gracilis became the 

 accepted types of the genera Climacograptus, Dicranograptus, Bicellograptus, and 

 Goinograptus respectively. 



Hall says little or nothing of the structure of the Graptolites, merely remarking 

 that they had a " semi-calcareous body with a corticiform covering." As regards their 

 zoological affinities, he considers that they have a close analogy with Virg ularia . 



