BALANUS. 31 
Parietes : the longitudinal ribs on the internal surface are either feebly, or, im the 
lower part, strongly developed; their basal ends are only just perceptibly denticulated. As 
already stated, in about half the specimens, there were no traces of parietal pores; in the 
other half there were either distinct or obscure pores; the pores are circular, generally of 
unequal sizes, and never large; in the same individual they would sometimes be almost 
wholly absent in some of the compartments, and quite plain in the other compartments. 
The radii are either moderately wide or rather narrow, and have their upper margins very 
oblique, and not distinctly arched, and not quite smooth: their sutural edges are very 
finely crenated, the teeth or septa not being denticulated. ‘The upper margins of the az 
are rather less oblique than those of the radii: their sutural edges are barely crenated. 
The dass is thin, and without any trace of pores; the upper surface is sometimes furrowed 
in radiating lines. 
1]. Bazanvs 1ncuusus. Tab. II, fig. 5a—by. 
B. nec porietibus, nec radiis poris perforatis ; basi poris perforata: testé rufo-fusca : 
radits latis, marginibus superioribus aut non obliquis aut modice ; aciebus suturalibus cum 
septis plané denticulatis: scuto sine adductoris cristd: tergi calcare subangusto. 
Neither walls nor radii permeated by pores; basis porose; shell reddish-brown; radii 
broad, with their upper margins not oblique, or only moderately oblique; sutural edges 
with plainly denticulated septa: scutum without an adductor ridge; tergum with the spur 
rather narrow. 
Var. (a) (fig. 5c, 5d), with the shell elongated in its rostro-carinal aais ; basis narrow, 
clasping the stem of a zoophyte ; lateral compartments much broader than the almost linear 
rostrum, carina, and carino-lateral compartments. 
Var. (6), with rough longitudinally folded walls, and with the summits of the radii forming 
an angle of about 45° with the basis. 
Fossil in Coralline Crag; Sutton and Gedgrave; attached to foliaceous Bryozoa; Mus. S. Wood, 
Bowerbank. Var. a, Coralline Crag, Sutton, attached to cylindrical branches of corals; Mus. S. Wood, 
Bowerbank. Var. 6, attached to shells, Osnabruck, Hanover, Mus. Lyell; Bunde, Westphalia, Mus. 
Krantz. 
My materials consist of a beautiful series of specimens in Messrs. Wood and Bower- 
bank’s collections; but unfortunately only a single young specimen had its opercular valves 
preserved. Not one specimen of the very curious variety (a) had opercular valves, yet I 
cannot feel any doubt about its being only a variety, caused by its attachment to a thin 
cylindrical branch of a coral, instead of to a foliaceous Bryozoon ; it will, however, be con- 
venient to give a separate description of this very remarkable form. With respect to 
var. (4), both sets of specimens came to me from the Continent, with the name of 
