IANTHINA. 179 



days." Mr. Arthur Adams has also furnished some 

 important information* with respect to the habits of 

 the Ianthina and the structure of its float. He says, 

 " The animal floats shell downwards, with the vesicular 

 buoy above it directed backwards. The anterior part of 

 the foot is mobile, free, rounded and dilated, and the 

 sides are usually folded inwards, forming a shallow cup, 

 which embraces the smooth anterior rounded end 

 of the float. When the animal wishes to bring its head 

 to the surface of the water, this part of the foot is made 

 to glide over the back of the float. Thus the animal 

 can raise and lower itself at pleasure by means of its 

 own float." . . . . " When the animal is weakly or 

 dead, the float readily becomes detached, for there is no 

 organic connexion between it and the foot." [I may 

 suggest, by way of parenthesis, that when an Ianthina is 

 snapt up by a fish, its float would be detached and re- 

 main on the surface of the water. This may account 

 for the number of loose floats observed by Mr. Adams, 

 Dr. Wallich, and others.] " When a portion is cut off, 

 the float is enlarged at the end next the foot of the ani- 

 mal, and is not regenerated at the excised part." .... 

 " With a pair of sharp-pointed scissors I made incisions 

 into the floats, and allowed the air to escape, when the 

 animals gradually descended, and remained helpless at 

 the bottom of the vessel : the floats were not regenerated 

 or renewed during the period the animals remained alive. 

 Crepitating portions, when separated, continue buoyant 

 until the vesicles of which they are composed gradually 

 collapse from the escape of the air with which they are 

 distended; and the floats, when pounded in a mortar, 

 are readily reduced to a mucus." Professor Lacaze- 

 Duthiers has very lately (Ann. Sc. Nat. Dec. 1865) 



* Ann. & Mag. N. H. Dec. 1862. 



