The present treatise originally appeared in Danish as a University publication (Kjœbenhavns Universitets Festskrift, November 1919). In submitting it to the English public, I wish to acknowledge my profound indebtedness to Mr. G. F. Hill of the British Museum, who not only suggested the English edition, but also with untiring kindness has subjected the translation, as originally made by Miss Ingeborg Andersen, M.A. of Copenhagen, to a painstaking and most valuable revision.
