CIRRIPEDES. MOLLUSCA. BALANUS. 13 



Balanus diadema, BRUG. ; Encyc. Mtth., pi. 165, f. 13, 14. 



Coronula diadema, LAM. ; An. sans Vert., v. 652. LEACH ; Encyc. Brit. Suppl., iii. 

 171. BLAINV. ; Diet, des Sc. Nat., x. and xxxii. pi. 117, f. 4. SOWERBY ; Genera, 

 f. 1. BURMEISTER; JYaturgesch. der Rankenfttsse, 34, pi. 2, f. 1 - 14. 



Poly'Jepas diadema, GRAY; Annals of Philos., x. 105. 



Diadema vulgaris, SCHUMACHER ; Nuuv. Syst. des I'crs, 91. 



Shell usually cylindrical, with a conical summit, truncated at 

 tip, sometimes of an inflated or globose-conical form. The sur- 

 face is divided into twelve triangular compartments, six with the 

 apex downwards which are depressed, plain, and faintly striated 

 across ; and six with the apex upwards, each of which has four 

 rounded ribs, marked across with beaded folds or wrinkles ; orifice 

 one third, or more, of the diameter of the base, mostly closed by a 

 membrane, through a fissure in which, closed by two valves, the 

 arms are protruded. Beneath, arranged in six compartments, 

 each of which is excavated into three cells with a small, interme- 

 diate one at the circumference. Diameter 1 to 2 inches, height 

 an inch or more. 



It is distinguished from C. balcenaris by its more erect and elongated 

 form, its larger orifice, and the beaded wrinkles of the surface. 



GENUS BALANUS, LAM. 



The Balani or Sea-acorns are immovable in all their external 

 parts, and attach themselves generally to inanimate bodies, either 

 fixed or floating, though they are occasionally found attached to 

 lobsters, shells, corals, &c. 



BALANUS TINTINNABULUM. 



Shell purplish, conical, the six triangles with irregular, unequal 

 ribs, the intervening spaces sculptured across with distinct lines; 

 operculum rostrated behind. 



State Coll., No. 250. Soc. Cab., No. 2076. 



Lepas tintinnabulum, LIN.; Syst. Nat., 1108. CHEMN.; Conch., viii. t 97, 

 f. 828, 829, 830. GUALT. ; Conch., t. 106, f. H. RUMPHIUS ; Mus., t. 41, f. A. 

 KNORR ; Vergn. v. t. 30, f. 1. WOOD ; Index, pi. 1, f. 5. Gen. Conch., t. 6, f. 1. 



Balanus tintinnabulum, LAM. ; An. sans Vert.j v. 658. BRUG. ; Encyc. Meth., pi. 

 164, f. 5. SOWERBY; Genera, fig. 1. SCHUMACHER; Essai, fyc., 90. RAN- 

 ZANI ; Memorie, $*., 33, pi. 2, f. 2 - 4 GRAY ; Annals of Philos., x. 104. 



Shell conical, the sides more or less inclined, and sometimes 

 a little turgid ; color violaceous. Surface having the raised tri- 



