22 ECHINODERMATA. 



luxuriant flower or arborescence, constituting what are supposed ten- 

 tacula. The body of most specimens assumes the form of a horse-shoe, 

 crescent, or cucumber, and a stream of water, playing like a fountain, 

 is forcibly discharged from the posterior extremity. 



These general features of external aspect will probably enable the 

 student to distinguish a few species of the Holothurian tribe. But of 

 later years the progress of comparative anatomy, from the desire of ascer- 

 taining the precise position, form, and functions of every portion of the 

 animated frame, has threatened to disturb the facilities enjoj^d from 

 simple aspect, and has beset the study with higher obstructions. 



The reader must be sensible, however, that the uniform tenor of this 

 treatise, so far from contemplating the destruction of life, encourages its 

 careful preservation, as the best, and indeed the only means, of discover- 

 ing the nature of animals. 



The Holothuria forms a genus whose exact position is one of the 

 most doubtful in the Sijstcma NaturcE. It is not in immediate approxi- 

 mation to any other, for some great chasm seems to intercept it from all. 

 We cannot point out any genus, sufficiently distinguished, which either 

 precedes or follows it. 



The Holothuria pentactes is a large, strong, and vigorous creature. 

 But the distension of the body, the alteration of its figure, together with 

 the circumstances wherein it is found, and which attend its preservation, 

 induce considerable ambiguity respecting its utmost natural dimensions. 

 The unrestrained form of this animal, at ease, and in undisturbed 

 security, is a crescent, throughout two-thu'ds of its length. The ante- 

 rior part, which is retractile within the body, expands into ten beautiful 

 arborescent tentacula, bordering a broad disc, wdth the mouth in the 

 centre. An exterior smooth skm is here interj)osed between the head 

 and the shoulder, and the remainder of the body, decreasing from the 

 middle downwards, terminates in an orifice, discharging the continued 

 stream of water above alluded to. — Plate I. 



Five longitudinal rows of peduncles or suckers traverse the skin of 

 the whole body, commencing near the root of the tentacula, and termi- 

 nating at the posterior orifice, through whose adhesion the animal is 



