12 BASE 
ture elliptical; siphon dorsal. Obs. This genus differs from 
Orthoceras in the same manner that Ammonites differs from 
Nautilus, having its septa exceedingly lobated and sinuous. A 
Baculite might be described as a straight Ammonite. Known 
only fossil, in the limestone of Meestricht and Valognes. Fig. 
484, B. Faujasii. 
BA’LANUS. Lam. (An acorn, Gland de Mer, fr.) Order, Sessile 
Cirripedes, Lam. Fam. Balanidea, Bl. Descr. Shell composed 
of six valves, locked into each other, side by side, in a conical 
circle, closed at the base by a flat, cylindrical, or cup-shaped 
valve, by which it is generally attached, and at the apex bya 
conical operculum, consisting of four valves, in anterior and 
posterior pairs. Each valve of the shell is divided into a 
rough triangular portion, pointed towards the apex, and a flat 
area on each side. Obs. This description includes the AcastTa 
of Leach. Bauanus is the only genus of Sessile Cirripedes, 
the shells of which consist of six principal valves, except Coro- 
nula, the shells in which have no shelly base, are flatter, and have 
the valves of the operculum placed horizontally. The Balani 
are common in all seas, adhering to rocks, corallines, ship bot- 
toms, and to each other. The fossil species are found in the 
newest ‘strata, at Bordeaux, Paris, &c. Fig. 25. B. Tintinabu- 
lum. 26, Acasta Montagui. 27, Balanus galeatus. 
BALAN'IDEA. Bl. The second family of the class Nemato- 
poda, Bl. Sessile Cirripedes, Lam. 
BA’LEA. Gray. Colimacea, Lam. Deser. Spiral, turrited, con- 
centrically striated, sinistral, and covered with a thin brown 
epidermis; spire composed of numerous whorls, gradually in- 
creasing in size; aperture small, subquadrate; peritreme entire, 
slightly thickened, with a very slight fold on the columella, axis 
perforated. Obs. A genus of small land shells, found in moss 
at the root of trees in Britain, not very nearly resembling any 
other land shells, except Clausilia, of which they want the clau- 
sium. They have been placed in Helix by Ferussac, and in 
Pupa by Draparnaud. B. Fragilis, fig.296. Hela perversa, Fer. 
Pupa perversa, Drap. 
BAR’NACLES. Pernre.asmis, Avct. Called Anatifa by Lin- 
neeus and Lamarck, from the ancient notion that they were the 
eggs or embryos of the Barnacle Duck. See Anatifera. 
BASE. In all shells that are attached to marine substances, the 
base is that part of the shell which forms the point of attach- 
ment. Hx. The attached valve of Spondylus; the basal plate 
of Balanus; the lower part of the pedicle of Pentelasmis; in 
unattached bivalves, the margin opposite the umbones, where 
the part analagous to the foot of the animal protrudes; in spiral 
univalves, the aperture, which rests on the back of the animal 
when walking. Some authors have used the term base as simply 
