CEPHALOPODA. 221 



M. Sander Rang, who enjoyed ample facilities for 

 observing these animals at Algiers, does not coun- 

 tenance the notion of their sailing and rowing, 

 though his opinion can hardly counterbalance the 

 positive assertions of Madame Power. His remarks 

 on their motions are interesting. " Watching," says 

 he, " what took place around the Poulpe, which we 

 left contracted within the Argonaut shell, we saw 

 it extending itself from its shell, and protruding six 

 of its arms ; then it threw itself into violent motion, 

 and travelled over the basin in all directions, often 

 dashing itself against the sides. In these different 

 movements, the body leaned a little towards the 

 fore part of the shell, and the long slender arms, 

 much extended, and collected into a close bundle, 

 were carried before it as well as the tube, which 

 shewed itself open and protruded. The locomotion 

 was effected in the ordinary manner of Poulpes, 

 backwards, by contraction of the sac, and expulsion 

 of water through the funnel.* The disposition of 

 the animal and shell is the most favourable for aiding 

 the motion of the creature. The lightness of the 

 shell ; its narrow and keeled form ; its width, small- 

 est at the part which cleaves the water ; the mem- 

 brane smoothing all inequalities of the shell; the 

 bundle of arms extending behind, so as to offer 

 the least possible resistance ; the two arms, stretched 

 like a bridge over the cavity where the eggs are, as 

 if to throw off the water from that cavity ; all these 

 adaptations concur to facilitate the gliding of the 



* See fig. l,p. 217. 



