1884.] PROF. V. 3. BELL ON HOLOTHUROIDS. 5(>3 



1. Studies in the Holotlmroidea. — V. Further Notes on the 

 Cotton-Spinner. By Prof. F. Jeffrey Bell, M.A., 

 Sec. R.M.S. 



[Eeceived November 1, 1884.] 



Owing to the kindness of Mr. Snell of Truro, who has, on two 

 occasions, heen so good as to forward me specimens of the Cotton- 

 Spinner, I am ahle to give some little further information with regard 

 to the characters of this incompletely-known Holothurian. Unfor- 

 tunately, however, all the trouble and care that has been taken has 

 not been rewarded by the arrival of living specimens in London ; the 

 investigation into the physiology of this interesting form and the 

 complete knowledge of its minute structure, which is best gained from 

 a study of perfectly fresh specimens, will, I doubt not, be undertaken 

 at the Biological Laboratory soon to be erected at Plymouth. 



The specimens forwarded to me came from Durgan, a fishing- 

 village seven miles from Falmouth, where they are reported to be 

 abundant at a depth of 10 to 20 fathoms ; they appear to be objects 

 of superstitious dread to the fishermen, who always throw overboard 

 the " Sea-cows," as Mr. Snell says they call them. 



When still comparatively fresh, Holothnria nigra is seen to he of a 

 bright yellow colour beneath, and has the suckers distributed with 

 fair regularity over that surface, though a bare patch is often 

 apparent anteriorly ; the dorsal surface is black, slimy, and papillose, 

 but without suckers ; the cuticle is exceedingly thin, and often comes 

 off in flakes, leaving patches of a more dead hue exposed. The 

 lower surface is flattened, and the upper slightly convex ; or the 

 whole creature may be more rounded or sausage-shaped. The 

 cloacal orifice looks upwards. The body-wall is firm and smooth, 

 but varies in the extent to which it is slimy to the touch. 



In a specimen which was more or less flattened the length was 

 observed to be 165 mm., and the breadth of the body 38 ; a sausage- 

 shaped example measured 135 mm., and had the greatest girth of 

 its body 120 mm., so that it was very stout. 



After standing in alcohol (40 per cent, over proof) for an hour, 

 specimens were observed to have stained the fluid ; the solution was 

 fluorescent, giving a greenish colour with reflected and a yellow with 

 transmitted light. This colour does not seem to be lost by exposing 

 the alcohol to sunlight ; at any rate, it has not disappeared after an 

 interval of more than six weeks' exposure to daylight. 



Like many other characteristic colouring-matters, that of the 

 Cotton-Spinner does not present us with any absorption-bands. As 

 will be shown, however, it has some very striking resemblances to 

 the colouring-matter described by Prof. Moseley as antedonin \ 



1 Quart. Jouru. Micr. Sci. xyii. 1877, p. 8 et seq. 



