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Show 1884.] PROF. F. J. BELL ON HOLOTHURIA NIGRA. 373 of Natural History,' vol. xv. (1845). In a note on Irish Echino-dermata, read to the Dublin Natural-History Society, Prof. Kinahan mentions by name " Cucumaria niger, Couch,"1 as having been taken on the west coast of Ireland (Natural .History Rev. vol. vi. p. 369) ; in the succeeding year (cf. op. cit. vol. vii. p. 394) Mr. Foot has a brief note on the habits of what he calls " II. niger." Finally, Prof. Moseley has under his care a specimen in the University Museum at Oxford, which bears the name of Holothuria nigra, and is said to have come from the Scilly Islands. The collection of the British Museum contains five specimens which appear to me to be referable to the species figured by Peach but never yet so described as to be, with certainty, recognized by the systematic zoologist. The specific characters by which it may be distinguished appear to be :-Suckers almost entirely confined to the trivial surface ; tentacles twenty; body elongated ; integument very soft. Colour (in spirit) more or less completely black ; in life the lower surface and " the thornlike appendage on the back" are stated to be of a light green colour. Body-wall rather thick. Calcareous spicules rare ; the only forms observed were perforated with four large holes, somewhat as in Thyone fusus (cf. Diiben and Koren, Vetensk. Akad. Handlingar, 1844, pi. v. fig. 42). The oesophageal annularia of moderate size; radials and interradials subequal, longest along their middle line, which forms a well-marked, rather broad keel. Polian vesicle large. The Cuvierian organs packed into a large compact mass. Measurements:- Length 120 110 105 Greatest breadth . . 37 4 40 The following observations may be made on the just enunciated specific characters. Though the creature has been called "Nigger " by the fisherman, and nigra, by the naturalist, it does, as Peach tells us, vary in colour, being " all shades, from sienna to rose-colour and delicate pink." The suckers do not, in spirit-specimens, appear to be arranged in definite rows. They are rather thickly scattered over the whole of the trivial surface; at any rate, Peach is in error in considering that this creature is remarkable for the possession of four rows of suckers. From Peach's illustration it would appear that the dorsal papillae, and especially those at the sides of the body, are much more prominent in living than in preserved specimens. In the description of the pharyngeal ossicles I have adopted the nomenclature proposed by Prof. Moseley, in his description of a remarkable Holothurian pharynx2; here annularia only, and no pharyngealia, are developed. The scarcity of calcareous spicules was to be expected as soon as one knew that " on exposure to air they lose their tenacity and crumble to pieces ; " but, on the other hand, i The addition of the name of Couch must be an error; I find no reference to the species in tbe < Cornish Fauna.' 2 Q. J. M . S. xxiv. (1884) p. 255. |
