32 



ECHINODERMATA. 



beds of the Laminaria or tangle, which is not improbable, if portions of 

 this vegetable product are devoured. But it rather appears that a more 

 solid foundation is congenial to its nature, for the suckers, which consti- 

 tute its chief security, are not well adapted for application to such 

 flexible substances. Possibly the food is yet unknown. The animal's 

 mouth is susceptible of great dilatation, opening almost as wide as the 

 entire diameter of the disc. 



During this remarkable expansion of the specimen, Plate I., 

 I dropped various animal substances into the cavity, nothing vegetable 

 being then at command. But none proved acceptable. All were found 

 afterwards in the vessel. 



With so firm a hold, and such a capacious mouth, the Holothuria, 

 if carnivorous, would be a dangerous enemy. Its extreme timidity, 

 however, most conspicuous on all occasions, prohibits our supposition of 

 its acting offensively against any part of the animated creation, and 

 hence the tentacula are probably to be chiefly protected. 



Nevertheless, the nature of the food is a question of some interest. 

 Those genera of the Echinodermata, with which it is most immediately 

 classed, are highly carnivorous, the Asterias and Echinus. The true 

 nature of its sustenance might affect its position in the Systema. 



It is vexatious to witness the subjects of observation pining away 

 before us, from inability to ascertain their food. 



The Holothuria pentactes dwells in various parts of the Scotish 

 seas. It is found about the mouth of the estuary of the Forth ; and in 

 the course of years, some straggling specimens occur to the westward, 

 it is said even as high as Newhaven, where stream tides rise seventeen 

 or eighteen feet. If the fishermen may be credited, it is recovered 

 from the depth of ten or twelve fathoms. But where particularly abun-. 

 dant, as at Lerwick, whence many fine specimens have reached me, I 

 have been informed that they dwell at the depth of one or two fathoms 

 from the surface, and very near the shore. 



The wonted colour of the Holothuria pentactes is different shades of 

 brown or purple. Two, which I considered varieties, were dingy white. 

 One of these shewed great versatility of form. This specimen lost the 



