AND PELAGIC SURFACE-SWIMMING SPECIES. 301 



unexpanded conditions. These cells are smaller than the others, being of about one fourth 

 the length of the larger ones. They are of an ovoid form, but slightly beat. They have 

 a thread which, when protruded, has a very wide, fusiform commencement, round which 

 is wound a spiral line, bearing spines, the succeeding fine portion of the thread being 

 unarmed. In the contracted condition a trifling invagination takes place in the first 

 broad part of the thread, as in the largest cells ; and the spines are of course reversed in 

 inclination, being turned backwards towards the base of the cell. These cells seem to 

 form an interesting transition towards the peculiar three-spined thread-cells of Hydroids ; 

 they occur on the base of the animal. 



A single specimen of this interesting form was dredged in the South Pacific Ocean in 

 lat. 39° 4' S., long. 105° 5' W., on Nov. 1st, 1875, from 2025 fathoms. A closely similar 

 specimen was likewise obtained which differed only in having darker, madder-coloured, 

 radial streaks on the disk, and in being much larger, measuring 10 - 5 centim. in diameter 

 of the disk. It was abnormally irregular in having 52 instead of 48 marginal tentacles, 

 caused apparently by the intercalation of an additional half-system of 4 tentacles ; but it 

 may evidently be referred to the same species. It was dredged, together with a large 

 number of other Actininge, in lat. 33° 42' S., long. 78° 18' W., on Dec. 17th, 1875, from 

 1375 fathoms. 



It seems necessary to refer the above-described form to a new genus. It resembles 

 the genus Discosoma* in being rigid and unable to contract the disk and cover the 

 tentacles, but differs from it in that the tentacles are here not very numerous, and that 

 they are provided with a knob at the tip, as in Corynactis. Similar or kindred forms 

 were often dredged in deep water by the ' Challenger.' They seem closely allied to the 

 simple disk-shaped corals, such as Steplianophyllia, in which the tentacles are also 

 knobbed and disposed at the margin, and on the surface of the disk, in a closely similar 

 manner. They have further similar thread-cells to these solitary corals, and, indeed, ap- 

 pear to differ from them only in having no calcareous corallum developed. Indeed, in one 

 species of Stephanopliyllia, obtained in deep water, the calcareous skeleton was in a most 

 rudimentary condition, being a mere delicate network of calcareous trabecular So like 

 in appearance were these forms of Actininse to the living corals, that it was only by 

 feeling them as they were found in the dredge that I became convinced that they had no 

 calcareous skeleton, and I macerated several in caustic potash in the hopes of finding 

 traces of a corallum present in them. They seem to approach these disk-like corals very 

 closely, and possibly to represent forms from which the corals were developed. 



Corallimoephtts RiGiDifs, n. sp. (Plate XLV. figs. 9 & 10.) 



A form allied to that just described, and evidently to be referred to the same genus, 

 was obtained amongst the Moluccas in 1425 fathoms. The body of the animal is some- 

 what cartilaginous, tough and firm, maintaining its shape, and not contractile. Its form 

 is that of a truncate cone, the base being of less than half the diameter of the oral disk. 

 The lateral walls of the body present smooth, slightly projecting, rounded ridges or costae, 



* Vide MM. Edwards & Haime, I. e. tome i. p. 255. 



