THE ANNALS AND MAGAZINE OF NATURAL HISTORY. [FIFTH SERIES.] No. 59. NOVEMBER 1882. XXXIV. — Preliminary Notice of Cephalodiscus, a new Type allied to Prof. AllmarCs Rhabdopleura, dredged in H.M.8. 1 Challenger: By Prof. M'Intosh, F.R.S.* [Published by permission of the Lords Commissioners of the Treasury.] A shoet time ago Mr. Murray, Director of the ' Challenger '-Expedition Commission, drew my attention to an anomalous organism which had been relegated to the Annelida ; and though on examination it proved to be an ally of Rhabdo-pleura, Prof. Allman and Prof. Busk (both of whom had arrived at the same conclusion in regard to its systematic position) most kindly and disinterestedly insisted on my describing it, especially as Phoronis had just been the subject of investigation. This remarkable form was dredged at Station 311 (in the Strait of Magellan f) , January 11, 1876, in lat. 52° 50' S., long. * Communicated by tbe Author, having been read (with accompany-ing drawings) at the Southampton meeting of the British Association, August 1882. t The Strait of Magellan appears to harbour several molluscoid rari-ties. Thus the remarkable Ooodsiria coccinea of Prof. P. O. Cunning-ham (Trans. Linn. Soc. vol. xxvii. p. 489, tab. 58. fig. 3) is a social Asci-dian with an elongate (above 2 feet) lobed, rooted, fibro-gelatinous mass of a vivid scarlet colour, " reminding one in some measure of the fleshier Alcyonoid polyps," in which minute flask-shaped animals are imbedded in circumferential cells. The animals are about a line in length, and, so far as can be made out from the sketches, appear to be social Ascidians. From the same neighbourhood the curious Pynra Molina of Blainville also comes. Ann. & Mag. N. Hist. Ser. 5. Vol. x. 23 '