274 POPULAU HISTORY OF THE AQUARIUM. 



and the shell called Taper Nautilus, or xlrgonaut, belongs 

 to an Ocytho'e, another member of the class Cephalopoda. 



When Se^jia vulgaris is first placed in a vessel, it darts 

 about in a restless manner, by forcing jets of water from 

 a funnel which is situated beneath the body. Having in 

 this manner explored every part of its prison, it will hold 

 itself in suspense in mid-water, all the time flapping with a 

 pair of fin-like wings. When at the bottom of the tank 

 it has a very curious way of crawling by means of its 

 arms, which are then bent angularly for the purpose. The 

 manner in which the little creature changes colour is very 

 surprising. '^ AYe can scarcely," says Mr. Gosse, ^' assign 

 any proper hue to it. Now it is nearly white, or pellucid, 

 with a faint band of brown specks along the back, through 

 which the internal viscera glisten like silver. In an in- 

 stant, the specks become spots that come and go, and 

 change their dimensions and their forms, and appear and 

 disappear momentarily. The whole body, arms, fins, and 

 all the parts which before appeared free, display the spots, 

 which, when looked at attentively, are seen to play about 

 ill a most singular manner, having the appearance of a 

 coloured fluid injected with constantly varying force in the 

 substance of the skin. Now the spots become rings, like 



