. Annual report . hes composed ofmore tubular thecae, with less overlap, looser arrangement, smaller deviationfrom the direction of the axis of the branch and straight, not mucronateapertures. 1 Bost. Soc. Nat. Hist. Memoir. 1899. , GRAPTOLITES OF NEW YOKK. TART 1 On the other hand, I) i d y m < i g r a p t u s gracilis, a form withextremely long filiform thecae in the mature stage, possesses in its proximalpart shorter, tubular thecae, of the Bryograptus type of thecal structure,thus indicating an opposite path of development to that observed inGoniograptus, but which also finds i
. Annual report . hes composed ofmore tubular thecae, with less overlap, looser arrangement, smaller deviationfrom the direction of the axis of the branch and straight, not mucronateapertures. 1 Bost. Soc. Nat. Hist. Memoir. 1899. , GRAPTOLITES OF NEW YOKK. TART 1 On the other hand, I) i d y m < i g r a p t u s gracilis, a form withextremely long filiform thecae in the mature stage, possesses in its proximalpart shorter, tubular thecae, of the Bryograptus type of thecal structure,thus indicating an opposite path of development to that observed inGoniograptus, but which also finds its expression in the ontogenetic develop-ment of the branch [see fig. 12]. As noted before, the directions of the branches in the proximal partspresent also an ontogenetic development, indicative of phylogenetic stagespassed. Both the direction of the branches and the character of thethecae tend, hence, to support the same view, viz that the branches, thoughcomposed of thecae were connected into physiologic Fig. 12 D i dy m o gr ap t us gracilis Tornquist. Enlargement of the specimenfigured on plate 11, figure IT to show more distinctly the sicula and the progres-sive lengthening- of the thecae. Deep kill. .\6 The writer has endeavored to demonstrate in the paper on Goniograptusthat, not only the branches, but in fact the entire colonies of graptoliteswere organisms approaching closely to the character of individuals. Onefinds among the colonies all gradations from loose aggregates of individualsforming colonies to organisms in which, by division of labor, consequentsuppression of individuality and the presence of common organs, the colonyalso morphologically approaches closely to the character of a sole individual,as in the Siphonophora. The graptolite rhabdosomes now present, besides the ontogeneticcharacters of the proximal parts described above, various other features,which are suggestive of the physiologic individuality of the colonies. Someof these are the presenc
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