438 MOLLUSCA. 



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 anal tube, differ but. little from those of the Ana- 

 tifae. 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, Sec, on the coast of Europe, are, in a man- 

 ner, covered with a species of Balanus, the Lepas balanus^ L., 

 Chemn., VIII, xcvii, 826, 1(1). Naturalists have separated 

 from it 



The AcAST^, Leach, whose base is irregular, convex towards the 

 exterior, and Avhich does not become fixed; most of them are found 

 in sponge(2); 



The Coxi^, Blainv., the tube of which has but four salient pieces(3). 



The AsEM^, Ranzani, where the tube has no decidedly salient 

 pieces(4); 



The Pyrgom^, Savigny, whose tubular position, forming a strongly 

 depressed cone, has but a very small orifice, almost like the shell of 

 a Fissurella(5); 



The OcTHOsi^, Ranzani, which have but three salient pieces in 

 the tube and only two valves to the operculuni(6); 



The Creusive, Leach, with four salient pieces, and two valves to 

 the operculum(7). 



(1) Add, Lepas balano'i'dis, Cliemn., VlII, xcvii, 821 — 825; — L. tintinnabulum, 

 lb., 828 — 831; — L. minor, Vo., 827; — L. ^oros«, Id., xcviii, 836; — L. verruca, lb., 

 840, 841; — L. angusta, lb., 835; — L. elongata, lb., 838; — L. patellaris, lb., 839; — 

 L. spinosa, lb., 840; — L. violacea. Id., xcix, 842; — L. iulipa, Ascan. Icon., X; — L. 

 cylindrica, Gronov., Zooph., XIX, 3, 4; — L. cariosa. Fall., Nov- Act. Petrop., II, 

 vi, 24, A, B. 



(2) Acasta Montagui, Leach, Edinb. Encyc, copied Blainv., Malac, Ixxxv, 3; 

 — Lepas spongites, Poli, 1, vi, 5. 



(3) Conia radiata, Blainv., Malac, Ixxxv, 5. 



(4) Lepas porosus, Gm., Qhemxi; VIII, xcviii, 836, 837, Encyc. Method., pi. 

 165, f. 9, 10. 



(5) Pyrgoma cancellaia, Lesich, loc. cit., copied Blainv., Malac, Ixxxv, 5. 



(6) Lepas Strcemii, Miill., Zool Dan., Ill, xciv, 1 — 4. 



(7) Creusia spiyiulosa. Leach, loc. cit., copied Blainv., Malac, Ixxxv, 6.' 



