58 ECHINODERMATA. 



mens will prove the source of many entertaining, instructive, and inte- 

 resting observations. 



There is extraordinary difficulty in determining the difference of 

 species of an animal appearing in such disproportion as the extension 

 and contraction of the tumid and empty Holothuria. The identity of 

 the species may be most readily mistaken : also there may be varieties 

 which require to be seen under the most favourable conditions. 



From various circumstances, I feel little surprised that the species 

 of the Holothuria are multiplied infinitely beyond the truth. If I my- 

 self be not mistaken in regard to species, I must conjecture that the 

 Holothuria fusm extends a foot in length when full grown. The body 

 of a specimen, nearly white, extended eight inches by about fifteen lines 

 in diameter. It was almost cylindrical throughout, with very obtuse 

 extremities. It assumed a curvature at the bottom of a jar. The ten- 

 tacula, of a reddish colour, were never completely displayed : a gangrene 

 consumed the skin of the lower extremity, and the animal died in five 

 weeks. 



Another specimen taken considerably eastward of the Isle of May, 

 was of dingy brown, and five inches long in its contracted state. It 

 survived but a short time, and died without evolution of the organs. 

 Many specimens are dark grey. Could the fishermen be credited, the 

 dimensions of specimens occurring to them, have exceeded the propor- 

 tions here assigned by me. But independently of their propensity to 

 exaggeration, farther than the Sea Pudding previously described, the 

 Holothuria seems utterly unknown to them, both by name and appear- 

 ance. I never met with one who knew the existence of such an animal, 

 far less the variable and perfect form which it assumes. 



I was unable to determine the species of the two last named, from 

 not having obtained a sufficient view of either. Reflecting on the first, 

 however, since the date of occurrence, I think it may have possibly been 

 the long species described in the next paragraph. 



I have been alike perplexed by others of ample dimensions, though 

 never unfolded so much as to shew their actual formation. 



The Holothwia fusns readily covers itself with whatever flexible or 



