CIRRHOPODA. 289 



attached to various bodies, the aperture of which is more or less closed by 

 two or four valves. This tube is formed of various pieces, which appear 

 to be detached, and separated in proportion as the growth of the animal 

 requires it. The branchiae, mouth, articulated tentacula, and the tube, 

 differ but little from those of the Anatifae. In Balancs properly so called, 

 the tubular portion is a truncated cone formed of six projecting pieces, 

 separated by as many depressed ones, three of which are narrower than 

 the others. Their base is usually formed of a calcareous lamina, and fixed to 

 various bodies. The four valves of their operculum close the orifice exactly. 



The rocks, shells, &c., on the coast of Europe, are, in a manner, covered 

 with a species of Balanus, the Lepas balanus, L. 



Naturalists have separated the Acaatx, most of which are found in sponge, 

 the Coniae, Blainv., the Asemx, Ranzani, the Pyrgomae, Savigny, the Qdho- 

 siae, Ranzani, the Creusias, Leach, and the Diadema, Ranz. 



2 M 



