978 MB. J. T. JOHNSON ON THE [NoV. 28, 



14. Terias senegalensis, var. bisinuata Butler. 

 One female. 



15. Belenois mesentina Cramer. 

 A pair. 



16. Glutophbissa saba, var. oontbacta Butler. 

 One male. 



17. Leucebonia thalassina Boisd. 

 One male. 



7. Note on the Habit and Mode of Growth of the Corals 

 belonging to the Genus Plewocorallium. By James 

 Yate Johnson, C.M.Z.S. 



[Eeceived 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 Pleuroco milium. Whilst the species of CoraUium, 

 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. 



When 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 correct- 

 ness of Dr. Gray's view, and to suggest another conclusion. 



In describing the only known specimen of Pleurocorallium in - 

 derense (loc, cit.), I stated that some zoophytes of rare occurrence 

 at Madeira were grovA'ing 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 hori- 

 zontally. But can we suppose it possible that they would take in 



