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Show 1867.] DR. J. S. BOWERBANK ON HYALONEMA MIRABILE. 19 his former opinion that Hyalonema belonged to the " Barked Alcyo-naria," and announces his belief that it should be arranged with the Zoanthidce. In the Society's 'Proceedings' for 1864, p. 265, M . Barboza du Bocage, Director of the Museum of Natural History at Lisbon, has described a specimen of Hyalonema, which was found off the coast of Portugal, near the mouth of the River Sado. This specimen does not appear to have had any portion of a basal sponge appended to it. The author designates the protuberant organs on the coriaceous coat of the spiral column as polypes; and describes what he conceives to be a row of twenty tentacles around the central orifice, and a second circle within the first one of conical elevations which appear to him to be rudimentary tentacles, which he describes thus : - " Les tentacules sont cle forme triangulaire, comprimes des deux cotes, ii bords parfaitement lisses, et a pointe mousse et arrondie. Ceux du premier rang sont plus larges a la base; et leur bord anterieur est plus convexe, et en forme de bourrelet arrondi." The author subsequently obtained two other specimens of the same species, and described them in the same work for November 1865 : in p. 663 he writes :-"Quoique 1'hypothese du parasitisme des polypes soit aujourd'hui en faveur, soutenue qu'elle est par de grandes autorites scientifiques, les resultats de mes observations sur les specimens du Portugal me semblent plus favorables a 1'hypothese contraire." The author then proceeds to give the reasons for this conclusion under five separate heads. The observations of M . Barboza du Bocage do not throw much light on the subject of the disputed nature of Hyalonema; and the proofs he offers under five separate heads go rather to prove the spongeous nature of Hyalonema than its polypiferous nature. In no. 1 he merely states that no spongeous base has been found on the Portuguese specimens; but this may also be stated of the greater number of specimens from Japan. He also states, in no. 2, that the corium polypigerum in one specimen from Portugal envelopes the whole of the axis entirely, from the smallest extremity, for two- or three-fifths of its length. And this is just the condition of the specimen, supposing its lower portion to have been enveloped by a basal spongeous mass, as is the case with the most perfect specimens from Japan ; and the gradual diminution in the size of the oscula (polypiferous orifices of the author) is quite in accordance with their characters as oscula of an extended cloacal appendage to a sponge of such a structure. In no. 3 the author describes the structure of the corium polypigerum, or coriaceous bark of Gray, in terms which apply equally well to the similar parts of Hyalonema mirabile, in which siliceous spicula are also abundant, intermixed with extraneous particles of sand; but the intermixture of the latter would greatly depend on its local surroundings while living. In no. 4 the granu- , lated appearance of the surface of the corium is described as "due to the presence of an infinite number of regular spicula dispersed in masses and bristling with points." And in no. 5 he states that each polype is sustained by a siliceous structure of filiform spicula, disposed |
