548 IANTHINID^E. 



IANTHINA. 



Shell ventricose, subglobular, thin, translucent, smooth 

 or striated. Aperture more or less triangular, outer lip 

 sub-emarginated, columella straight. No operculum. 



Animal with a large muzzle-shaped head, bearing a 

 tentacle and a sustentacle on each side, but presenting no 

 traces of eyes. Foot short, secreting a float composed of 

 numbers of cartilaginous vesicles, on the under surface of 

 which the egg-vesicles are borne. Sexes separate. Bran- 

 chiae of two plumes. Lingual band without axile teeth, 

 but having two series of lateral uncini, slender and narrow, 

 obtuse above and pointed below (Loven). 



These animals are pelagic, floating about on the surface 

 of the ocean, often in myriads, and apparently always 

 gregarious when in their natural haunts. The float at- 

 tached to the foot was first (as well as the shell itself) 

 noticed by Fabius Colonna in 1(516: he designated it by 

 the expressive and appropriate name of spuma cartilaginea. 

 Ouvier observed that there was no anatomical connection 

 between the two bodies. This was confirmed by Dr. 

 Coates, who, in the fourth volume of the " Journal of the 

 Academy of Natural Sciences of Philadelphia,"" gives an 

 interesting account of his experiments on the float in the 

 living animal. He found that it was entirely secreted by 

 the foot, and that when a portion was removed, the injury 

 was rapidly repaired. The egg-bags are attached to the 

 under surface of the float, and, as well as that organ itself, 

 appear to differ in form and arrangement in the different 

 species. Dr. Coates remarks that the animal seems to 

 occupy considerable time in the deposition of its eggs, the 

 l>n^s nearest to the extremity of the float being constantly 



