The Arenig graptolite genus Pseudotrigonograptus Mu & Lee, 1958

Abstract

Topotype material of Graptolithus ensiformis J. Hall, 1958 (= Retiolites ensiformis J. Hall, 1865) is revised and compared with three dimensional material from the Gaspé peninsula. This latter is shown to be scan-dent quadriserial, is considered conspecific with the topotype material, and with recently described, etched collections from Spitsbergen (Fortey 1971). It is concluded that the genus Pseudotrigonograptus Mu & Lee (1958) based upon P. uniformis is a valid genus with dear priority over Trisitichograptus Jackson& Bulman (1970), a genus erected to embrace the morphology of the Spitsbergen triserial rhabdosomes and at the same time exclude the invalid Trigonograptus lanceolatus Nicholson (1009).