In _Bal. glandula_, in D, the parietes of the compartments, without several were examined, might be thought to be solid, and therefore this species might be wrongly placed in F; on the other hand, the fossil _B. unguiformis_, in F, often has porose parietes, and such specimens would naturally be placed in D. Lastly, without care, _B. flosculus_ might be thought to have a membranous basis, and so get placed in E. The genus Pachylasma, without an examination of the animal's body, might easily get misplaced in the wrong genus, amongst the species in the last section (F) of Balanus, yet there can be no doubt that Pachylasma belongs to the Chthamalinæ. _Section_ A. 1. BALANUS TINTINNABULUM. Pl. 1, fig. _a_-_l_; Pl. 2, fig. 1 _a_-1 _o_. LEPAS TINTINNABULUM. _Linn._ Syst. Naturæ, 1767. ---- ---- _Ellis._ Phil. Transact., vol. 50, 1758, Tab. 34, figs. 8 and 9. ---- ---- _Chemnitz._ Neues. Syst. Conch., 8 B. (1785), Tab. 97, figs. 828-831. BALANUS TULIPA. _Bruguière._ Encyclop. Meth., 1789; sed non _B. tulipa alba_, in _Chemnitz_; neenon _B. tulipa_, _O. F. Müller_, Zoolog. Dan.; neenon _B. tulipa_, Poli, Test. ut. Siciliæ. ---- ---- _G. B. Sowerby._ Genera of Recent and Fossil Shells, Tab. Genus Balanus. LEPAS CRISPATA (_var._) _Schröter._ Einleitung Conch. vol. iii, Tab. 9, fig. 21. ---- SPINOSA (_var._) _Gmelin._ Linn. Syst. Nat. ---- TINTINNABULUM, SPINOSA, CRISPATA ET PORCATA. _W. Wood._ General Conchology, 1815, Pl. 6, figs. 1, 2. Pl. 7, figs. 4, 5. Pl. 8, figs. 1-5. BALANUS TINTINNABULUM. _Chenu._ Illust. Conch.[87] ---- D'ORBIGNII (_var._) _Chenu._ Illust. Conch., Tab. 6, fig. 10, sed non Tab. 4, fig. 13. ---- CRASSUS (Foss.) _Sowerby_ (!). Min. Conch., 1818. Tab. 84. [87] Chenu gives several admirable figures of this species; but he confounds some forms certainly distinct under this name, for instance the _B. tulipiformis_ of this work. _Shell varying from pink to blackish purple, often striped and ribbed longitudinally: orifice generally entire, sometimes toothed. Scutum with the articular ridge broad and reflexed. Tergum with the basal margin generally forming a straight line on opposite sides of the spur._ _Var._ (1) communis (Pl. 1, figs. _a_, _b_, _f supra_; Pl. 2, figs. 1 _a_, 1 _c_, 1 _d_, 1 _e_, 1 _i_, 1 _k_): _conical or tubulo-conical; smooth or moderately ribbed longitudinally; colours varying from purplish-pink to blackish-purple; often in obscure longitudinal stripes; orifice of shell rounded-trigonal_. _Var._ (2) vesiculosus (_young_) (Pl. 2, fig. 1 _h_): _exterior surface of the scuta impressed with small square holes, arranged in two or more rows, radiating from the apex of the valve_.