Introduction During the last four or five decades the two chief objects in the study of the graptolites have been, first, the refinement in classification, together with the careful description of new species and the determination of ontogenetic and phylogenetic relations; and, secondly, the determination of the exact stratigraphie or zonal distribution of the graptolites and the correlation of these zones over wide geographic areas. Questions of habitat and mode of distribution were considered only incidentally, though such keen students as Lapworth, Wiman, Ruedemann, and Hahn have dealt with these problems separately. The conclusions reached by Lapworth2 and published in Walther’s “Ueber die Lebensweise fossiler Meeresthiere” have been quite generally accepted. His belief is that the graptolites, which lead a floating existence either as holoplankton or epiplankton (attached to sea-weeds), sank to the bottom of the deeper littoral, where no other organisms lived and where they were buried in the fine . . .
- Received 30 April 1917.
- © 1917 Geological Society of America