250 , EVENINGS AT THE MICROSCOPE. 



faecal matter of a yellowish-brown colour is collected in two 

 small masses, near the extremity. Along the under side 

 runs the ovary, which in this specimen contains two long 

 oval eggs in advanced development ; from their transpa- 

 rent brightness, I suspect the young are produced before 

 birth. I think I can detect a contractile bladder, but am 

 not certain. 



The dorsal region of the trunk is marked with strong 

 rugged lines running longitudinally ; these look like corru- 

 gations 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 detected 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 head is rotating, but the foot is almost wholly withdrawn 

 within the body ; in which state the resemblance to a 

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



