GRAPTOLITES OF NEW YORK, PART 2 187 



more elaborate description of the genus, to a part of which we will recur 

 presently. 



Finally Wiman | iqoi, p.ioj | has described from etched specimens the 

 structure of a species which he refers to Inocaulis (I. musci f orm i s), 

 stating at the same place that he now considers as belonging to the same 

 genus another form which he formerly placed under Ptilograptus (I . 

 s u e c i c a). 



If these two species are properly placed, the structure of the genus 

 Inocaulis has been demonstrated. The question which hence concerns us 

 next, is whether Wiman's species are to be considered as true representa- 

 tives of Inocaulis. If we compare his figures with those of I. plumu- 

 1 o s u s which as the genotype is the last court of appeal, we find at once a 

 striking difference in habit, I . p 1 u m u 1 o s u s having very thick, massive 

 branches which are so densely covered with minute, fingerlike processes 

 [see pi. 7, fig. 2] that no interspaces are left, while the Swedish forms 

 have thinner branches which consist of but few tubes and their branchlets 

 are relatively large and far apart. That these differences are not of a 

 fundamental character appears from the fact that in both the branchlets are 

 composed of several thecal tubes, which empty upon them [see pi. 7, fig. 1], 

 and from the consideration that the branches of I . p 1 u m ulosus being 

 so much thicker and composed of so many more thecal tubes, the emptying 

 groups of thecae will naturally be more crowded upon the surface of the 

 massive branches. 



The Swedish species are obviously identical in habit with forms 

 described under Acanthograptus in Canada [Spencer 1884] and there is no 

 doubt that Wiman's species as well as Pocta's should be properly referred 

 to that genus [seep. 192]. The latter, however, is undoubtedly so closely 

 related to Inocaulis that the conclusions obtained as to its structure are on 

 the whole transferable to Inocaulis, and we therefore here refer the reader 

 to the description of the structure of Acanthograptus. 



If we restrict the genus Inocaulis as here proposed, all the species 

 referred to it by Pocta will also have to be removed to Acanthograptus, and 



