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Show 132 MR. W. L. SCLATER ON A N E W [Feb. 16, The genus Stephanotrochus belongs to the section of the Madre-poraria known as the Madreporaria aporosa, to the family Turbi-nolidae of Milne-Edwards and Haime, and to the section Discocyathoida of Martin Duncan (3), which is characterized as follows : - " Simple Turbinolidae, discoid in shape, not increasing much in height with growth. Free or not. "With or without pali in one crown. Columella variable; epitheca also." Stephanotrochus moseleyanus agrees in every way with the above definition except in the point about the pali, since in S. moseleyanus there are distinctly two crowns of pali. IV. Distribution of the Genus Stephanotrochus. All the species of Stephanotrochus hitherto described are deep-sea forms, the depths from which they come varying from 410 to 1009 fathoms ; S. moseleyanus comes from a depth of 570 fathoms. The geographical distribution, considering the fewness of the specimens dredged, is extraordinary ; seven specimens have beeu obtained belonging to five different species, procured from such distantly separated places as Pernambuco, the Azores, Sydney, N.S.W., and the Faroe Channel. As was mentioned above, S. moseleyanus was dredged in the warm area of the Faroe Channel, where the bottom temperature is very high, 46°-5 F. V. Anatomy of Stephanotrochus moseleyanus. The soft tissues of the polype extend from the edge of the cup some distance down the outside wall of the corallum, gradually thinning out; the line of the extension of the soft parts is marked in the dry corallum by the change of colour from a glistening white to a greyish blue, the colour of the basal parts uncovered by soft tissues. As far as I was able to observe, the enteric cavity does extend round the edge of the theca to the outer side, so that the tops of the smaller septa would probably stand up free in the enteron ; the primary and secondary septa are so extremely exsert that the tissues are abnormally stretched to cover them, and so have by the action of the alcohol been split. This would rather seem to confirm Koch's theory (5) that the theca is formed from the fused peripheral ends of the septa. The oral disk, the tentacles, except at their tips, and the outer soft wall of the coral are all of a dark madder-colour ; this colour is due to a substance called by Prof. Moseley (6) Polyperythrin ; it is distinguished by peculiar properties : it is insoluble in water, glycerine, alcohol, ether, ammonia, potash, or picric acid, but is soluble in strong hydrochloric acid ; it is also distinguished by a peculiar absorption spectrum, a broad black line including the line D. Prof. Moseley found it in Stephanotrochus diadema, in Flabeltum, Fungia, and Ste-plMnoplnjllia, and many other Ccelenterata. The soft wall of the coral is divided up by a series of longitudinal furrows, which correspond to theinsertionsof the mesenteries ; the ridges between the furrows are further crossed by a number of transverse ridges, so that the whole wall assumes a very wrinkled |