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Show 978 MR. J. Y. JOHNSON ON THE 14. TERIAS SENEGALENSIS, var. BISINUATA Butler. One female. 15. BELENOIS MESENTINA Cramer. A pair. 16. GLUTOPHRISSA SABA, var. CONTRACTA Butler. One male. 17. LEUCERONIA THALASSINA Boisd. One male. 7. Note on the Habit and Mode of Growth of the Corals belonging to the Genus Pleurocorallium. By JAMES YATE JOHNSON, C.M.Z.S. [Received November 2, 1899.] In my communication to the Zoological Society on the Coralliidce of Madeira (P. Z. S. 1899, p. 57) nothing was said as to the cause or meaning of the peculiar habit and mode of growth of the four known species of Pleurocorallium. Whilst the species of Corallium, such as the red coral of the Mediterranean, branch in all directions and put forth their polype-cells on all sides of the branches, the Pleurocorallia ramify more or less in one plane and their polype-cells are confined to one face of the branches. W h e n Dr. Gray first alluded to the matter (P. Z. S. 1867, p. 125) he said," I have no doubt that it (the coral under description) grows out horizontally from the rocks, and that they (the polype-cells) arise from the upper surface of the branches." This would appear to have been only a conjecture; but in his Catalogue of Lithophytes or Stony Corals in the British Museum (p. 24) he went further, and described them as " growing horizontally from the sides of rocks," without citing any authority for the statement. The facts about to be mentioned seem to throw doubt on the correctness of Dr. Gray's view, and to suggest another conclusion. In describing the only known specimen of Pleurocorallium m - derense (loc. cit.), I stated that some zoophytes of rare occurrence at Madeira were growing parasitically upon it. Two of these were branched specimens belonging to the genera Suberea and Stenella, and they were seated on different parts of their host at a distance from each other. The point to which I wish to draw attention is, that both these Alcyonarians had grown in the plane of the host. If that had extended horizontally, they too had extended horizontally. But can we suppose it possible that they would take in [Nov. 28, |