CIRRHOPODA. 275 



ages that adhere to the external base of the whole of the cirri, or of part 

 of them. 



The two principal valves, of the most numerous species (PENTALASMIS, 

 Leach), resemble those of a Mytilus. The Anatifae adhere to rocks, piles, 

 keels of vessels, &c. 



BALANUS, Bruguieres. 



The principal part of the shell of the Balani consists of a testaceous tube 

 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 Anatifse. In BALANUS 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, Lin. 



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

 the Conue, Blainv., the AsemoE, Ranzani, the Pyrgoma, Savigny, the Octhorue, 

 Ranzani, the Creusitf, Leach, and the Diadema, Ranz. 



T 2 



