8o 
BULLETIN OF THE BUREAU OF FISHERIES. 
There are some acute crests at the insertion of the depressor muscle, and in old individuals the whole 
inner surface is slightly roughened. The spur is not thickened inside, but the scutal border, near the 
basal angle, is raised in a thin laminar flange (pi. vm, fig. 3, 4). The inner faces of both scuta and 
terga are white. 
The mandible (fig. 10, D) has four slender teeth and a lower point. The second tooth stands 
midway of the cutting edge. There is a copious beard along the lower margin, and there are some 
hairs near the cutting edge. The maxilla (fig. 10, C) has a notch at the upper angle and numerous 
larger and smaller spines; both upper and lower margins are bearded. The first cirrus (fig. 10, A) 
has subequal rami of 16 and 14 segments, which are rather densely spinose; and while convex at the 
sides, the segments do not protrude. The second cirrus has subequal rami of 18 and 22 segments, more 
copiously spinose than the first cirrus. Third cirrus, with 25 and 29 segments. The fourth to sixth 
cirri are longer and more slender, and are similar in armature. The fifth cirrus has rami of about 48 
segments, several of the lower ones difficult to distinguish, as usual. Each segment is armed with two 
pairs of very long spines, with a group of quite small spines between and slightly below the large ones 
of each pair (fig. B, 32d to 34th segments of cirrus v). The posterior border of the cirri, in the basal 
half, is very minutely serrate or shortly spinulose. The penis (fig. 10, E) is remarkably short, only 
about 7 or 7.5 mm. long, very closely annulate, and wholly without hairs. 
This handsome barnacle is readily distinguished from B. corolliformis and B. hirsutus by the shape 
of the tergum, which has a spur distinctly removed from the baso-scutal angle of the plate, and the 
articular ridge does not project beyond the regularly concave scutal margin of the plate. In these 
characters, B. callistoderma is more like B. hoekianus, in which, however, the cuticle of the opercular 
plates and walls is not hairy, the tergum is much narrower, and the smooth sheath has a free lower 
edge, as usual in Balanus. In B . callistoderma the sheath is transversely ridged and continuous below 
with the rest of the plate, with no overhanging ledge. 
Genus ACASTA Leach. 
Acasta spongites japonica, new subspecies. [PI. xvi, fig. 1-9.] 
Type no. 38681 U. S. National Museum. 
Type locality : Albatross station 4936, off Kagoshima Gulf, in 103 fathoms. 
A form more closely related to A . spongites than to any other described species. The deep basal 
cup is about half the height of the carina, broadly ovate in contour. Externally it has fine, uneven 
circular striae and low, inconspicuous, narrow, longitudinal riblets, each terminating in a minute point 
on the upper margin. Inside there are no ribs and no teeth at the margin. 
The plates of the wall are only loosely connected, and have a few calcareous points or spines. The 
radii are narrower than the parietes. The carina is decidedly larger than the rostrum, quite concave 
within. The carino-lateral plate has a narrow parietal area, its basal width contained 2 to 2.3 times 
in that of the rostro-lateral plate, thus being much wider than in A. spongites. The rostrum is the widest 
and shortest plate. Internally the plates of the wall show only the weakest traces of longitudinal ribs 
below the sheath, which is continuous with the surface below it and occupies more than half the length 
(pi. xvi, fig. 6, 7, 8, 9, interior views of rostrum, rostro-lateral, carino-lateral and carina). The sheath is 
glossy, and in the carina and carino-laterals is ridged across with smooth, thread-like riblets. The 
rostro-laterals are less strongly ridged, and in the rostrum the ridges are very weak and low. 
The scutum (pi. xvi, fig. 4, 5) is concave outside, with sculpture of low transverse lamellae and 
delicate radial striae. The articular ridge is rather low and about half the length of the tergal margin. 
There is no adductor ridge. 
The tergum (pi. xvi, fig. 1, 2) has a concave band from apex to the spur, and is sculptured elsewhere 
with transverse threads. The low articular ridge is continuous with a low ridge which continues upon 
the spur. The spur is united until near the end with the baso-scutal angle, in this respect being unlike 
A. spongites. 
This form differs from A. spongites of the Mediterranean, etc., chiefly by the wider parietes of 
the carino-lateral plates, the absence of an adductor ridge in the scutum, and the different shape of 
