4(3 ECHINODERMATA. 



the Holothuria to seize and retain animals larger than itself, and pos- 

 sibly render them its prey. 



Attempting to solve the question of aliment, has led me into this 

 prolix detail, for the purpose of shewing of what importance it would be 

 to naturalists studying the properties of living beings, which, indeed, 

 is the best foundation of zoology. Though some creatures survive in- 

 credibly long without visible sustenance, perhaps secreting an invisible 

 pabulum from the circumambient fluid, all nature opposes the perma- 

 nence of life without nutrition ; thus, however gradual the decline, it 

 prevails at last. 



The body of this species of Holothuria is totally covered by flexible, 

 extensile papiUae, alike instrumental in adhesion, and in aiding progres- 

 sion. It is by their means that an artificial shelter can be framed occasion- 

 ally of the fragments of shells and fuci. Doubts have originated whether 

 others, such as the Holothuria inhcErens, do not occupy a tube with a 

 close extremity. But I have seen nothing to indicate that any of the 

 tribe are so protected. Most specimens are bare, though. i]\efusus is al- 

 ways disposed to attach fragments within reach of the papillae or 

 suckers to the body. 



During quiescence, or while floating, the skin resembles shagreen, 

 the suckers being scarcely, if at all, prominent. When somewhat pro- 

 longed, the whole body is invested by a woollen-like coat, and when, ex- 

 ercising then* proper functions, they extend about three lines, with the 

 extremity applied as an enlarged disc to some solid adjacent surface, 

 Plate XI. fig. 2. 



The number of these organs is gi-eat, but it has not been ascertained 

 that those of this species are distributed in any regular arrangement ; 

 they overspread the whole skin. In certain species of HolothuriaB they 

 are disposed in definite rows, or longitudinal bands, specifically cha- 

 racteristic. On gross computation the suckers of this specimen, Plate IX., 

 exceeded two thousand. When disengaged they are very flexible, mov- 

 ing freely around, and each has an independent action. When occu- 

 pied in fixture, it appears, from the most accurate microscopic observa- 

 tion practicable, that this is a simple application of the extremity some- 



