250 THE AQUARIAN NATURALIST. 



CHAPTER XXIV. 



SIPUNCULUS. 



" From Nature's chain, whatever link you strike, 

 Tenth or ten thousandth, breaks the chain alike." 



EVERY traveller must have observed, on approaching 

 the boundary-line which separates two countries dif- 

 fering in language, how gradually the transition is 

 effected by the interposition of some unintelligible 

 patois, which, partaking equally of both, belongs to 

 neither. Precisely in the same manner the Zoologist, 

 as he nears the confines of the subkingdoms, or even 

 the provinces marked out upon the grand chart of 

 Natural History, is sure to encounter forms of life so 

 doubtfully combining the characters of most opposite 

 races of beings, as to defy the nicest criticism to pro- 

 nounce on which side of the border they ought to claim 

 allegiance a fact of which the Sipunculi, the subjects 

 of the present chapter, afford us a very interesting 

 example. 



The Holothuriae, as we have seen, notwithstanding 

 their elongated form and soft integument, still retain 

 the locomotive suckers which so peculiarly charac- 

 terize the star-fishes and the sea-urchins ; and from 



