Abstract
While accompanying the Oxford University Hudson Straits Expedition in 1931 to Akpatok Island in Ungava Bay, North Canada, the writer found that in the horizontally bedded limestones of Ordovician age one stratum alone was graptolitiferous. This contained a vast number of individuals in all stages of development, nevertheless all of the same species. When treated suitably with acid, specimens could be isolated from the matrix and thus a complete ontogeny has been worked out.

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