. Annual report . Fig. 91 Phyllograptus an prustif olius Hall, a View of a rliabdosorac. etched out oflimestone. Seen from the reverse lantisicular) side. x4 h Sicular end of rhabdosome, seen fromthe obverse (sicular) side. xU c Rhabdosome seen from the sicular end. Shows the apertures ofthe sicula (in the center), of the first two thecae (Hanking- the sicula), and of the earliest portionsof the branches. x6. (/Transverse section through a rhabdosome, showing the central coeno-sarcal canal and its four longitudinal septa. x6 (Copies from Holm) Diplograptus have now however been demonstrated to
. Annual report . Fig. 91 Phyllograptus an prustif olius Hall, a View of a rliabdosorac. etched out oflimestone. Seen from the reverse lantisicular) side. x4 h Sicular end of rhabdosome, seen fromthe obverse (sicular) side. xU c Rhabdosome seen from the sicular end. Shows the apertures ofthe sicula (in the center), of the first two thecae (Hanking- the sicula), and of the earliest portionsof the branches. x6. (/Transverse section through a rhabdosome, showing the central coeno-sarcal canal and its four longitudinal septa. x6 (Copies from Holm) Diplograptus have now however been demonstrated to be not the result of thecoalescence of two branches, but of the budding of thecae of one series alter-nately on opposite sides. It is, hence, evident that the two genera are ofentirely different structure. Subsequent observers, as Lapworth, Tullbergand Tornquist, have all corroborated Halls conception of Phyllograptus, andTullberg recognized the close relationship between Tetragraptus and Phyllo-graptus. GRAPTOLI
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