Report on the zoological collections made in the Indo-Pacific Ocean ...

358 COLLECTIONS FROM MELANESIA.1 millim. in diameter at its base, placed oa the larger and mediumsizedbranches. Axis of soft joints firm, brick-red in colour; thatof interuodes crimson, traversed by numerous longitudinal canals inthe stem and larger branches, in the small branches deeply channelledby longitudinal forrows.Spicules of general cortex :—(i.) Largei', fusiform, the ends ratherblunt, the shaft stout, beset with numerous strong and prominenttubercles, their ends strongly microtuberculate, irregularly distributed'jver the spicule; size •21 by •0()2 millim. (ii.) Smaller, subcubical,looking as if formed by an aggregation of tubercles like thoseof (i.) ; diameter •07 millim. Spicules of verrucoe (iii.) :— Longitudinal,fusiform, with blunt ends, provided with numerous and strongtubercles of a length equal to half the diameter of the shaft of thespicule ; size ^21 by •035 millim. (iv.) Horizontal, fusiform, taperingto sharp points, tubercles numerous but small and sharp ; size as (iii.\Hah. Port Molle, Queensland, 12-20 fms.Two dry specimens represent this beautiful species. The commonstem of the largest is 31 millim. long, its total height 130 millim.(5 inches), its maximum width 76 millim. (3 inches). The speciesdiffers from M. ocliracea externally by the presence oftwo kinds ofzooids, by the sleudcrness of the stem, and the slight difference inthickness between the main and the lesser branches, by the greaterrelative length of the internodes and the rounded outline of the joints,the almost complete anastomosis of the branches, and the whitishground-colour of the cortex ; in its minute characters it is distinguishedby the long cortical spicules being stouter and about halfas long again as in M. ocliracea.^ and by the stronger tuberculationof those of the verrucse. Although, as in the cases of Alcyoniumand Sarcophutum, Xenia and Heteroxenia, two otherwise nearlyrelated qenera have been shown to be distinguished by the characterof dimorphism in the polypes of one of the i)air, I do not knowanj- other case in which, as here, a species is referable on all othergrounds but this one character to the same genus as other specieswhich do not exhibit it.MOPSELLA.Mopsella, Gray, P. Z. 8. 1857, p. 284.Melitella, Graij, P. Z. S. 1859, p. 485.Both hard and soft axis perforated by longitudinal canals whereverstout enough to carry them. Cortical spicules of two kinds, fusiformand foliated (" Blattkcule," IvoUiker). The presence of this foliatedspicule distinguishes the genus from Melitodes and Acaban'a ; this, inconjunction with the perforation of the hard axis, from Clathraria.33. Mopsella textiformis,Melitsea textiformis, Lamarck, Mem. Mus. Hist. Nat. i. p. 412Lamouroiix, Polyp. Jlexibles, p. 4l!4, pi. xix. fig. 1.Melithaea textiformis, M.-Edicards ^ Haime, Uist._ Cor. i. p. 201.