BARNACLES OF JAPAN AND BERING SEA. 
77 
1 79 0 52', in 43 fathoms, 
Balanus hoekianus, new species. [PI. xm, fig. 3-7, pi. xv, fig. 1-2.] 
Type no. 38666 U. S. National Museum. 
Type locality : Albatross station 4778, Bering Sea, N. lat. 52 0 12', E. long 
seated on a gastropod shell ( Buccinum ). 
A species of the group G of Hoek; base excessively thin, partly membranous; plates of the wall 
solid, without pores; no radii. 
The shell and opercular plates are white throughout. Shape shortly subcylindric, flaring outward 
at the large triangular ovate orifice. The parietes are slightly roughened but not distinctly ribbed 
or sulcate, with no chitinous cuticle and no hairs. The alas are smooth, with extremely oblique upper 
margins, so that the peritreme is deeply serrate. Internally the walls have a long glossy sheath below 
which they are somewhat sulcate, chiefly at the base of attachment. 
The rostrum (fig. 8, A, internal view) is much the largest plate. Externally, while it is finely 
indistinctly rugose longitudinally, there is no distinct costation, and no trace of radii. Inside the 
sheath is tripartite. The carina (fig. 8, B) is strongly concave. The rostro-lateral plate is wide, tri- 
angular, with a well-developed ala but no radius. The carino-lateral plate is narrow, recurved, with 
the ala wider than the parietal area. Inside 
the sheath is bipartite. The strongly recurved 
carina is V-shaped above, with wide alre and 
smooth, undivided sheath (fig. 8, B, inside 
view). 
The base is an excessively thin transparent 
film, calcareous at the edges, membranous in 
the middle. 
Height of the shell 8 mm. ; diameter of 
the base 8 mm. 
Mandible (fig. 9, B) has four principal teeth. 
The upper two are rather long and acute, the 
second one in the middle of the edge. The 
third and fourth teeth are blunt, and there 
are two denticles between them. The lower 
point is short and slightly bifid. The lower 
edge of the mandible is heavily bearded. The 
two mandibles are exactly similar. 
Maxilla (fig. 9, C) has an even edge except for a notch below the upper two large spines. There 
are six or seven large spines and a few smaller ones below the notch. A band along the edge of the 
maxilla and below the lower angle is bristly, and there are a few hairs along the upper edge. 
The first cirrus (fig. 9, A) has unequal rami of 9 and 13 segments. Those of the longer ramus pro- 
trude slightly, and all are densely hairy. The second cirrus has rami of 9 and 1 1 segments which 
are convex on the anterior side but do not protrude; third cirrus has unequal rami with 12 and 13 seg- 
ments. The other cirri are longer, the sixth with 23 segments, each with three pairs of spines, the 
lower pair rather small. (Fig. 9, D, 10th and nth segments of cirrus v.) 
The scutum (pi. xm, fig. 3, 4, 5) is moderately thick. It flares outward and is twisted toward 
the apex. Externally it is indistinctly marked with fine, weak growth-striae and rather widely 
spaced growth-arrest lines which are scarcely raised. Inside there is a short but well-developed 
articular ridge, about one-third the greatest length of the plate. The articular furrow is narrow and 
distinct though not deep. There is no adductor ridge, though a noticeable thickening extends down- 
ward from the lower end of the articular ridge, representing a vestigeal adductor ridge. A shallow 
oblong pit marks the insertion of the depressor muscle. 
The tergum (pi. xm, fig. 6, 7) is very thick for so small a plate, white, the scutal margin concave, 
carinal margin short, strongly convex. The spur is long and narrow, separated from the scutal margin 
Fig. 8 . — Balanus hoekianus . 
A, rostrum; B, carina. Internal 
views. 
