74 
bulletin of the bureau of fisheries. 
B. rostratus agrees with B. porcatus Da Costa in the porose parietes, solid radii and base, but differs 
in having the adductor ridge of the scutum wholly free from the articular ridge, and by the absence of 
any distinct articular furrow. In B. porcatus and B. nubilis the articular furrow of the tergum is deep. 
The wholly white plates are a further distinguishing feature. In B. porcatus the tergum usually has a 
purplish spot on the inner face, and a purplish beak. 
Balanus rostratus apertus, new subspecies. [PI. xii, fig. 4, 7; pi. xiii, fig. 1, 2, 8, 9.] 
Cotypes no. 38667, 38668, 38669, U. S. National Museum, all from station 4778. 
Type locality : Albatross station no. 4778, Bering Sea, N. lat. 52 0 12', E. long. 179° 52' in 43 
fathoms. Living embedded in sponges. Also stations 4777 and 4779, on Petrel Bank, Bering Sea, 
in 52 fathoms. 
The shell is white, subcylindric or conic, with convex sides and a large, triangular-ovate orifice, 
frequently as large as the base. The parietes are marked with fine, waved, transverse striae, and 
Fig. 6 . — Balanus rostratus apertus. A, ist cirrus; B, mandible; C, maxilla; D, 15th and 16th segments of cirrus v. 
sometimes bear short, acute spines projecting outward and downward, each prolonged upward in a 
short rib. These spines appear in groups and are not numerous when present. The radii are much 
wider than in B. rostratus, transversely striated, with the upper edges parallel to the base. They 
are only very little sunken below the parietes. Internally the plates are deeply, closely, and sharply 
sulcate, and the bases of the parietes have square holes as in B. rostratus. The smooth sheath is 
nearly half the length of the shell. The stout, poreless, calcareous base is generally concave externally. 
The rostrum is very wide, about as wide at its summit as at the base. Two specimens measure, 
(a) height 46, greatest diameter 33, length of aperture 19 mm., length of tergum 22 mm.; (b) height 
45, greatest diameter 31, diameter of base 24 mm., length of aperture 26 mm. 
The scutum is extremely strongly ridged transversely, the ridges much narrower than the inter- 
vals; deeply and closely striated longitudinally, the striae weaker near the edges. Inside there is a 
rather narrow, not very high, articular ridge, but only the trace of an articular furrow. The adductor 
ridge is rather well developed, long, and wholly free from the articular ridge throughout. The 
