WHEEL-BEARERS 285 



The dorsal region of the trunk is marked with strong 

 rugged lines running longitudinally; these look like cor- 

 rugations of the integument, but I incline to think them 

 the strongly developed muscles for the retractation of the 

 foot. Muscles are seen running through the joints of 

 the foot, until they can no longer be traced, from their 

 tenuity. The viscera can be demonstrated with difficulty, 

 partly owing to the longitudinal muscles, which are so 

 strong and close, and partly from the incessant contraction 

 and elongation of the parts, which drive the internal 

 organs hither and thither. It refuses, you see, to swallow 

 carmine, which might have assisted us. 



This singular animal is lively in its motions, especially 

 in the protrusion and retractation of the extremities. These 

 are constantly alternating, and a very curious sight it is to 

 see the immense length of foot suddenly thrust forth from 

 the body, in which it had been completely hidden, the 

 starting out of the horizontal processes, and the diverging 

 of the long toes as these are successively uncovered. The 

 latter do not seem to be often used as instruments of pre- 

 hension or adhesion. Indeed the animal does not appear 

 very much given to change of place, but lies in the water, 

 alternately contracting and elongating. Frequently, as the 

 foot is thrust out, the body is made to bend forward so as 

 to form a right angle (see the engraving, in which the 

 animal is thus represented at a; b represents it when 

 the head is rotating, but the foot is almost wholly with- 

 drawn within the body ; in which state the resemblance to 

 a telescope, or to a nest of glass-tubes, is striking). 



The last specimen of this class of tiny favorites that I 

 shall show you is one of more than ordinary beauty. It 

 is the Two -lipped Tube -wheel of the Horn wort (Limnias 



