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Show 374 PROF. F. J. BELL ON HOLOTHURIA NIGRA. [May 20, I must again draw attention to the danger to spicules of maceration in weak spirit \ and express a hope that this communication will lead to the acquisition of some fresh specimens. If, however, the " Nigger" has but little protection from calcareous plates, he has, as a " Cotton-spinner," a means of offence which causes him (to again quote Peach) to be "held in great detestation, from its throwing out what they (the fishermen) call cotton. ... It is extremely irritable, and on being touched or disturbed throws out a bunch of white tapered threads about an inch in length and one eighth in thickness; these soon become attenuated, and are drawn into very long threads of great tenacity. ... I have seen a crab so completely entangled in it as not to be able to move, and a fish only able to get away after a long struggle." This "cotton" is secreted by the Cuvierian organs, which are arranged in a mode as yet undescribed in any Holothurian. Figure of lower portion of tbe body of Holothuria nigra, opened along the dorsal middle line ; tbe Cuvierian organs (c) are seen in situ, as is tbe coil of tubes in tbe cloaca (cl). A bristle bas been passed into tbe rectal opening of tbe intestine, which bas been pusbed a little to one side. When the body is laid open by an incision through the dorsal middle line, the whole centre of the lower part of the ccelom is seen to be occupied by a compact mass, more or less pyriform in shape, quite solid and almost hard to the touch ; underlying this is the rectal portion of the intestine, while anteriorly it is hollowed out into a shallow cup, which supports a coil of the intestine (fig. 1). In a specimen 110 m m . long, the mass in question has its greatest length 39 mm.; 9 m m . forming the wall of the cup on the upper surface, where it was a little longer than elsewhere ; at its thickest 1 Journal Roy. Micr. Soc. 1882, p. 481. |