THYONE PAPILLOSA. 161 



cies in captivity : — " The surfaces of the body were at first 

 partially covered with fragments of Shells and Corallines, 

 which were evidently retained by the suctorial powder of the 

 papillae ; and the animal on being kept a day in sea- water 

 threw them off. It had a slow progressive movement, 

 slower than the shadow of the dial, which was effected by 

 elongating the papillae of one part, fixing them to the plate, 

 and then drawing itself forward by again contracting those 

 elongated parts. But the papillae were oftener used for tlie 

 purpose of anchors than of feet, the creatures being of an 

 indolent and immovable character. When stationary it 

 was ever slowly changing its outward form ; it was now 

 shortened and swollen in the centre ; then it would relax 

 itself and become cyhndrical; again, one part would be 

 blown out, and another drawn in with a deep stricture, as 

 if a thread had been tied round ; or, again, the contraction 

 would begin near the head, which is then made very nar- 

 row, and would spread backward, the anterior portion re- 

 covering its original diameter as the wave of constriction 

 passed away ; and sometimes the constriction will spread 

 in the opposite direction. It often raised the posterior ex- 

 tremity a httle from the surface of the plate and to one 

 side, but I never saw any current flow from the aperture. 



M 



