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Show 796 PROF. J. R. GREENE ON A RARE MEDUSA. [Dec 16 the tropical and subtropical regions of the Atlantic, and in the ; while in latitude they extend from Nice and the Adriatic (C. marsupialis) to Santa Catbariua. According to Agassiz \ " Charybdea bitentaeulata, Q. and G., is a Campanella2; Ch. bicolor, Q. and G., constitutes a distinct genus, Quoya, Ag.; Ch. campanella, Less., may also constitute a distinct genus."-" It remains doubtful to what genus Lesson's Marsupialis flagellata, from New Guinea, ought to be referred. It constitutes, probably, a distinct genus, on account of its tentacles." Semper has given us precursory notices of some half-dozen species of Charybdeidee from the Philippine shores. The full details of his researches on these and other acalephs are looked forward to by many naturalists with great interest3. 1 ' Contributions, vol. iv. p. 174. 2 To which genus Agassiz also refers Charybdea capitulum, Q. & G. MS., De Bl. auct. See hi« explanatory note in ' Contr.' vol. iv. p. 169. 3 Semper found three species round the Pelew Islands. The first was more than 7" high, scarcely 3" across. Wall of disk extraordinarily thick, almost cartilaginous, quite colourless and transparent. The four tentacles were torn off just beyond their broad cartilaginous basal portions. A wide depending veil. Margin weakly lobed: just above it, in as many depressions capable of being closed, were the four marginal bodies. Manubrium dependent, not lobed. Central cavity of disk small. Lateral pouches very broad from their origin : between two contiguous pouches the umbrellar and subumbrellar walls were in contact, giving rise to the false appearance of a canal. Gastric tentacles in four double groups about the central cavity. But one (not-sexual) example (Taf. xxxix. f. 9). The disk of the second species was only li-" high, %'' across. Tentacles extensile to about twice the length of disk, with narrow basal lobes. Veil more complicated than in last species, always elevated, and held in this position by four subumbrellar septa, each springing from the mid line of a swelling, on the umbrellar aspect of which is the depressed cavity, opening outwards, whence the marginal body arises : septa perpendicular to subumbrella, and extending across the veil, which by them is hindered from assuming a horizontal position. Into each of the four broad lateral pouches freely project two sexual laminae, of which one arises on either side of the partition between two adjacent pouches. Sexual products discharged through a single series of small openings, which run close beside the attached border of each genital plate and lead into the lateral pouches. Manubrium short, four-lobed. Central cavity wide, with four double groups of gastric tentacles (Taf. xxxix. f. 8). A conspicuous nerve-ring exists in this and the preceding species. It pursues a zig-zag course (with eight octants), ascending slightly on either side of each marginal body, then descending and reaching its lowest point near the outer margin of the disk in the mid line of a tentacular lobe. The third species, scarcely £" high, diners in many points essentially from the two others. Tentacles four, ringed with brown and yellow, destitute of basal lobes. Of a beautiful yellow tint were likewise the sexual laminae and four groups of gastric tentacles. No veil. Margin strongly eight-lobed, bearing a shorter rudimentary tentacle between every two principal tentacles. The four very broad lateral pouches interrupted in their inferior third by thickenings of the substance of the disk, constituting the floors of the small cavities for the four marginal bodies. Each of the eight sexual laminae much indented about the middle of its free margin. Only two examples were secured ; so that some structural features could not be clearly determined (Beisebericht, 1863). A fourth species, fished up in M a y during a voyage from Manila to Komblon, was very like one of the forms just noticed. From July to September Semper |