Microscopical Essays. 



which it again loofens, and reding on the tail, flretches it out, as 

 in Fig. 39. It is eafy to fee from this account, that their manner 

 of walking is very analogous to that of various terreftrial and 

 aquatic animals. They walk very flow, often Hopping in the 

 middle of a ftep, turning and winding their body and arms every 

 way. Their ftep is fometimes very fmgular, as in the following 

 inflance : fuppofe the polype a b, Fig. 20, to he fixed by the tail 

 b, the body and arms being extended in the water, it firft bends 

 the fore-part towards the fubflance on which it is moving, and 

 fixes it thereto as at a, Fig. 21 ; it then loofens the lower end, 

 and raifes it up perpendicular, as in Fig. 22; now bending the 

 body to the other fide, it fixes the tail as in Fig. 23 ; then loofen* 

 ing the anterior end, it rifes up, as in Fig. 24. 



They defcend at pleafure to the bottom of the water, and 

 afcend again, either by the fides, or upon fome aquatic plants ; 

 they often hang from the furface of the water, relling as it were 

 upon the tail ; at other times they are fufpended by one arm from 

 it. They walk alfo with eafe upon the furface of the water. If 

 the extremity of the tail b, Fig. 7, be examined with a mag- 

 nifying ghfe, a fmall part of it will be found to be dry, and above 

 the furface of the water, and as it were in a little concave fpace, 

 of which the tail forms the bottom, fo that it feems to be fufpend- 

 ed on the furface of the water, on the fame principle that a fmall 

 pin, or needle, is made to fwim. 



Hence when a polype means to pafs from the fides of the glafs 

 to the furface of the water, it has only to put that part out of the 

 water by which it means to be fupported, and give it time to dry, 

 which it always does upon thefe occafions, They attach them- 

 / 4 felves 



