328 
of the lateral compartment, and a little tapering upwards. The 
lateral compartment is broadly triangular with arched sides, also 
rostrum is triangular with pointed apex. 
The radii and al ae are moderately wide with oblique and 
smooth margins; the opening of the shell is therefore irregularly 
star-shaped with 6 points. The radii and alae have no stripes on 
their external surface. 
The opening of the shell is oblique to the basis, the carina 
and carinolateral compartments are longer than the lateral and 
rostral compartments. Like other 
Conopea ’s also Balanus dentifer 
is situated with its carina up- 
most as compared with the coral 
colony, and has its opening fac- 
ing obliquely downwards, point- 
ing towards the base of the coral 
colony. 
At first sight the scutum 
seems to be longitudinally striate; 
this is due to small, radially ar- 
ranged groves in the rather pro¬ 
minent ridges of growth (Fig.65). 
The occludent margin has pro¬ 
minent teeth, but these teeth do 
not correspond with the growth ridges. The plate is a lit tle con- 
cave; the tergal third forms an almost right angle with the rest 
of the plate. The inner side has a feebly developed articular crista, 
but no ridge whatever for the adductor; on the other hånd the 
pit for the adductor is rather deep although not distinctly limited. 
The tergum has feeble although distinet lines of growth. The 
spur is distinet, twice as broad as long below the margin; the 
spur fasciole is rather deep. The internal surface exhibits almost 
no sculpturation; crests for the depressor are only faintly indicated 
and not distinctly limited. — The opercular plates, and especially 
the terga are very thin and brittle; this is the more curious as 
the walls are rather coarsely built and not fragile at all. 
The greater specimens have a rostro-carinal basal diameter of 
4,5 mm with a carinal height of 4 mm. 
Fig. 65. Balanus dentifer from 32° 15 ' N., 
128° 12’ E. Opercular valves. [X 17]. 
