During a visit to Stockholm last spring, Prof. Gustav Lindström kindly permitted the writer to examine the series of remains of Palöozoic fishes obtained from the Devonian of Spitzbergen by Dr. A. G. Nathorst, during the Swedish Geological Expedition in 1882. Some of the more prominent specimens have already been briefly noticed, with figures, by Prof. Ray Lankester; but the collection is worthy of a more detailed comparative study than that to which it has hitherto been subjected, and among the undescribed specimens most readily identified is a small fossil indistinguishable from the so-called “intermandibular arch” or “presymphysial bone” of Onychodus. Through the kindness of Prof. Lindström, this specimen has been forwarded to the British Museum for examination, and it forms the subject of the following remarks.