An interesting paper has lately been contributed to this Magazine (December, 1888, p. 532), by Dr. Gustav Lindström, of Stockholm, in which he announced his discovery of the earlier, or Nautilus stage, as he termed it, in several specimens of Ascoceras from the Silurian of the Island of Gothland. I find, however, in looking over the supplementary volume of the Syst. Sil. du centre de la Bohême,3 that Dr. Lindström's discovery has been anticipated by M. Barrande, who observed and described two of the normal chambers (Nautilus stage, of Lindström) attached to a specimen of Ascoceras Murchisoni from the Silurian strata (Étage E) of Karlstein in Bohemia.

A Very important discovery was made independently by Mr. Davison, and somewhat earlier by Mr. T. Mellard Reade, when they demonstrated that, on the hypothesis of the earth having cooled as a solid body, there is within it a certain level, which is called by Mr. Davison the “ surface of zero-strain,” and for which Mr. Reade has adopted the term “ level of no strain.” At this level compression ceases, and for a certain distance beneath it extension, or stretching of the layers of the globe, takes the place of compression.

On De La Beche's Geological Survey Map of Cornwall are three colours representing the associated rocks at, and on each side of the Manacle Point. The Point itself and for a considerable distance south of it is represented as a greenstone. Partially encased in the greenstone and to the south of it is gabbro, which forms the main mass of this rock in the Lizard district. On the north side of the greenstone which forms the extreme south wall of Porthonstock Cove is hornblende-schist, which with some serpentine and other rocks terminates against the killas, or slates near Porthalla.

Several observers with seeming good reason have drawn attention to the fact that the greenstone as represented on the map is made to cover much too large an area to the south, and that any one walking from this direction, or the reverse, finds gabbro where the former rock was expected to occur.