210 PENTACTvE. 



usual form. They have all the power of changing their 

 shapes in the strangest manner, sometimes elongating them- 

 selves like worms, sometimes contracting the middle of 

 their bodies, so as to give themselves an hour-glass shape, 

 sometimes blowing themselves up with water so as to be 

 perfectly globular. Many of the species are apathetic in 

 character, but others are exceedingly active, drawing in 

 and sending out their tentacula with great vivacity. 

 They are by no means elegant animals, being rather dis- 

 agreeable in aspect ; though when their tentacula are 

 expanded they cannot fail but excite some degree of ad- 

 miration even in the most careless observer. Their habits 

 are not well known, in consequence of their rarity and 

 the difficulties attending the observation of them. They 

 usually live among sea- weeds, or in mud, and are supposed 

 to seize their prey by means of their large tentacula. The 

 genus ranges over the greater part of the seas of the 

 globe, and there are many species which have, however, 

 from want of appreciation of essential characters by their 

 describers, been very dubiously characterised. 



The Great Sea-Cucumber is the largest of all the known 

 European species, and probably one of the largest Cucum- 

 aria: in the world, measuring when at rest fully one foot, 

 and capable of extending itself to the length of three. He 

 is the king of the Sea-Cucumbers, and seems to have 

 gathered the greater number of his subjects around him in 

 the Shetland seas, where his majesty was first recognised 

 as a native of Britain by Mr. Goodsir and myself in June 

 1 839. When he first came up in the hooks of the dreg, 

 an instrument used by the Shetlanders as a means of pro- 

 curing horse-mussels, Modiola vulgaris, called by them 

 Yoas-s, for bait, he astonished us with his monstrous ap- 

 pearance. The Shetlanders designate him by the some- 



