THE JANTHINA. 101 



these mollusks are found only in the high seas, at a 

 considerable distance from the shore, and that they 

 often remain at the surface of the water, where they 

 swim, like those just mentioned, with the assistance of 

 their small foot. It is said, that the middle line of the 

 belly appears like a leaf of silver, and is in a continual 

 undulatory movement. This little creature, scarcely 

 more than an inch in length, from its fine blue colour, 

 and the silvery hues which adorn some of its parts, has 

 a very elegant appearance when swimming in calm 

 weather at the surface of the sea. 



Another interesting creature is the janthina, the name 

 of which indicates the colour of the handsome shell, 

 which is a fine violet. The foot is distinguished by 

 a vesicular mass, which is said to be a sort of gela- 

 tinous or sub- cartilaginous froth, composed of small 

 cells, which can swell or contract at the will of the 

 animal. This creature inhabits the deep parts of the 

 sea in all warm latitudes. When the water is calm, 

 they may be seen floating on the surface, and some- 

 times in pretty numerous bodies. 



Over the vesicular buoy of the janthina, the animal 

 called the Portuguese man-of-war manages to cast his 

 thread ; and, like a spider entangling his prey in his 

 web, separates the shell from its buoy, and feeds on 



