3/4 



PROF. F. J. BELL ON HOLOTHURIA NIGRA. [May 20, 



I must again draw attention to the danger to spicules of maceration 

 in weak spirit 1 , 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 calca- 

 reous 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 the body of Holotlmria nigra, opened along the 

 dorsal middle line ; the Cuvierian organs (c) are seen in situ, as is tbe 

 coil of tubes in tbe cloaca (cl). A bristle has been passed into the 

 rectal opening of the intestine, which has been pushed 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 mm. long, the mass in question has its greatest 

 length 39 mm.; 9 mm. forming the wall of tbe cup on the upper 

 surface, where it was a little longer than elsewhere ; at its thickest 



1 Journal Eoy. Micr. Soc. 1882, p. 481. 



