A WELL-HOUSED SHELL-FISH. 191 



" Great fleas have little fleas 



Upon their backs to bite 'em ; 

 And little fleas have lesser fleas; 

 And so ad infinitum" 



But still it is true that the sphere of life is immensely 

 augmented by this remarkable device of making one 

 organism a microcosm on which other organisms 

 grow and revel ; making this stem, for example, a 

 region on which forests of other plants may wave, 

 and this strap a plain on which an enterprising poly- 

 zoan may build a populous city. 



We break off, with some excoriation of our fingers, 

 the outermost of these tough rootlets ; and discern 

 that their conical contour encloses a smooth-walled 

 chamber, sufficiently capacious to afford " ample room 

 and verge enough " for the residence of a luxurious 

 epicure, who has an oriental repugnance to locomo- 

 tion. How snugly ensconced is this overgrown limpet ! 

 You wonder how ever he got in, and how ever he was 

 to get out. The fact is, he got in a long while ago, 

 when he possessed the slenderness of youth, before 

 many of these rootlets were formed ; and as to getting 

 out, that contingency never entered into his brain (I 

 beg his pardon, he has no brain ; well then, into his 

 cephalic ganglion). What can a mollusk want more, 

 when he can feed on the wall of his bed-chamber, 

 and finds the savoury nutriment grow faster than he 

 can lick it off ? It would seem, indeed, as if the ex- 

 ertion of roaming over these narrow walls were too 

 great for him ; that, so far from complaining of the 



