Graptolite Assemblages and the Doctrine of Trends

Abstract

Viewed in the light of the Doctrine of Trends some interesting facts seem to emerge from the consideration of the graptolites characteristic of some of the zones or successive assemblages of these fossils. These seem to illustrate so clearly one of the fundamental tenets of the doctrine—namely, the necessity for a large degree of independence in the different characters—that they may be worth placing on record.