The holotypes of Buthotrephis grantii Dawson and Inocaulis vegetabilis Gurley are adjacent parts of a single 0.24 m wide colony from the Eramosa Member of the Lockport Dolomite in Hamilton, Ontario. The currently accepted name of Inocaulis vegetabilis, Thallograptus vegetabilis, is a junior objective syonym of T. grantii. Diplospirograptus dubius (Spencer) was found in the same horizon and facies as T. grantii. They are interpreted as a possible algal forest situated above an offshore deoxygenated sediment. The alternative graptolite or plant affinities of these two genera remain in doubt.