2 Bei, 
CRUSTACEA. 637 
A slit-like orifice between the opercular valves leads into the 
sac in which the body is lodged. The valves are two on each side, 
tergum and scutum. The tergum has three margins, the scutal, basal, 
and carinal ; on the basal margin a spur (cal/car) depends. The 
scutum has also three margins, the basal, tergal, and occludent, so 
called from opening and shutting against the opposite valve. Darwin 
Balanide, pp. 3—7.| 
Coronula BLAINY. Operculum not articulated together, com- 
posed of two or four calcareous pieces united by membrane. 
Coronula Lam., Diadema Ranzant. Shell depressed, conical or 
suborbicular, with very thick walls excavated internally by radiating 
cells. 
Sp. Coronula diadema L., Buatnv. Malacol. Pl. 86, fig. 4, Cuv. R. Ani. éd. 
ul., Mollusg. Pl. 139, fig. 2, on the Fin-fish, Balenenoptera, Balena 
longimana. 
Tubieinella Lam. Shell tubular or cylindrical, belted by trans- 
verse ribs or rings. Operculum with four valves. 
Sp. Tubicinella balenarum Lam. Ann, du Mus. 1. Tab. 30, fig. 1, Buarnv. 
Malacol. Tab. 86, fig. 5, GuéRIN Iconogr., Mollusg. Pl. 38, fig. 14; lives 
parasitically in the skin of the whale of the southern hemisphere (Balena 
: Mysticetus antarctica). 
Balanus Brua. (exclusive of some species), LAM. Shell conical, 
composed of six lamine or valves. Operculum articulated, subver- 
tical, consisting of four valves. 
Sp. Balanus sulcatus Lam., Lepas balanus L., Baster Natuurk. Vitsp. 1. 
Tab. x11. figs. 7—10; Balanus miser Lam., Encycl. méth. Vers. Pl. 64, 
fig. 4, &e. 
Acasta LEACH. 
Creusia LEACH. 
Pyrgoma SAVIGNY. 
Note.—On this and some other genera, proposed by Ranzant! and 
others, compare MILNE EDWARDS in the new edition of Lamarcr’s Hist. 
nat. des Anim. s. Vertébres, V. 1838, pp. 669—672. 
1 Observationi sui Balani ; Opuscoli scientifice di Bologna i. 1817, pp. 195—202, 
pp. 269—276, 11. 1818, pp. 63—93. 
