In erratic blocks of sandstone, found on the Disco shore of the Waigat, have been detected a Sigillaria and a species of either Pecopterisor Gleichenia, perhaps of this age; and probably much of the extreme northern coast of Ellesmere Land, and therefore, in all likelihood, the opposite Greenland shore, contains a clearly developed Carboniferous Limestone fauna, identical with that so widely distributed over the North American continent, and referable also to British and Spitsbergen species.
These include among others, Glossopteris browniana, Gangamopteris cyclopteroides, Sigillaria Brardi, Bothrodendron Leslii, Noeggerathiopsis Hislopi.
The Carboniferous forerunners of the tiny club-moss were then great trees with dichotomously branching stems and crowded linear leaves, such as Lepidodendron (with its fruit cone called Lepidostrobus), Halonia, Lepidophloios and Sigillaria, the largest plants of the period, with trunks sometimes 5 ft.
Apart from his more comprehensive works, his most important palaeontological contributions are perhaps his observations on the structure of Sigillaria (Arch.
In Sigillaria the latter form vertical rows, while in Lepidodendron the arrangement is a complicated spiral.