.328 NATURALIST'S CABINET. 



Mode of sailing Extraordinary sagacity. 



surface. Here it extends two of its arms up- 

 ward, which are eacli furnished at their ex- 

 tremity with an oval membrane that serves as 

 a sail. The other six arms hang over the sides 

 of the shell, and supply the place either of oars 

 or rudder. 



Multitudes of these curious animals may be 

 sometimes seen in some places, when the sea is 

 not agitated by winds, diverting themselves by 

 sailing about in this manner; but as soon as a 

 storm rises, or any thing gives them disturbance, 

 they retract their arms, take in as much water 

 as renders them somewhat heavier than that in 

 which they swim, and then sink to the bottom. 

 Several of them were observed by M. Le Vaillant 

 on the sea near the Cape of Good Hope ; and> 

 as he was desirous of obtaining perfect specimens 

 of the shells, he .sent some of his people into the 

 water to catch l hem; but, when the men had got 

 their hands witi'im a certain distance, they al- 

 ways instantly sank, and, with all the art that 

 could be employed, they were not able to lay 

 hold of a single one. The instinct of the animal 

 showed itself superior to all their subtilty ; and, 

 when their disappointed master called them away 

 from their attempts, they expressed themselves 

 not a little chagrined at being outwitted by a 

 shell fish. 



The shell of al]l this tribe is univalve, spiral, 

 involute, and mecobranaceous, with only a single 

 cell. 



