66 ECHINODERMATA. 



tributed. Scarcity and abundance are frequently unmeaning compara- 

 tives. Unpropitious circumstances, ravenous and inveterate enemies, 

 repress multiplication and diminish numbers. The excessive timidity of 

 the Holothuria indicates the liability of its external organs to injury, 

 while precluding all presumption of its subsistence by the capture of 

 living prey. 



No animal will more readily escape observation amidst miscel- 

 laneous marine collections. When free of adhesion, it contracts infi- 

 nitely without regularly assuming any determinate form : and afterwards 

 floats as a sphere, or an ovoid, or rolls over the bottom of its vessel. 

 Very few fishermen seem aware of the existence of such a creature. 

 None of those which I have carried to them, were recognised as having 

 been previously seen, and when brought to me by themselves, it has been 

 always in ignorance of their presence among other substances. While 

 endeavouring to obtain specimens, by describing the subject of the pre- 

 ceding paragraph to some of them, one present observed that it might be 

 the same as a substance he had found, which " he had pierced with a 

 knife, to discover whether it was alive ! " At length, some of the younger 

 fishermen, finding it their personal interest to extricate the Holothuria 

 from among the rubbish brought up by nets and dredges, they have en- 

 abled me to conduct my enquiries with greater facility. 



The difficulty and improbability of detaching this animal entire, 

 while unseen, from its firm adhesion at the bottom of the sea, and by the 

 rude apparatus employed, must be self-evident. Hence it is that natu- 

 ralists must be indebted chiefly to accident for perfect specimens. 



PLATE VIII. 



FIG. 1. Holothuria fusus. The Spindle Sea Cucumber or Sweep- Water. 



2. Another specimen, with the arborescencc partially protruding. 



3. The specimen, fig. I, in a dying state. The tentacular apparatus 



and intestines escaping. 



PLATE IX. The specimen, Plate VIII. fig. 1, having regenerated the 

 tentacula. a. 



