216 BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



The labrum has a rather shallow but wide median notch. There 

 is a group of five small denticles on one side, about nine on the 

 other (fig. 69(7). The first cirrus has unequal rami of 8 and 13 

 segments. The longer ramus is over one and one-half times the 

 length of the shorter, and has slightly protuberant segments. Cirri 

 ii and iii have also slightly protuberant segments; cirrus iii has 

 groups of erect spinules near the distal anterior borders of the seg- 

 ments. Cirri iv to vi have four pairs of spines on each segment, the 

 lower pair very small (fig. 69;, 5). 



The penis is rather short, tapers rapidly and is very densely, 

 indistinctly annulated. The distal half bears delicate, rather sparse 

 hairs, and there is a terminal pencil. The basi-dorsal point is blunt 

 but Avell developed. 



This is a small and delicate form of the group of B . hameri, closely 

 resembling that species, B. evennanni and B. amaryllis, in the form 

 and structure of the compartments of the wall and the basis. It 

 differs from all of these by the well-developed adductor ridge of the 

 scutum, which stands quite separated from the articular ridge, 

 though close to it, and also by the very broad and short spur of 

 the tergum, which has no longitudinal furrow and no infolding of 

 the sides of the spur fasciolc, and resembles the tergum of Armato- 

 l)alanus. The rami of the first cirrus are subequal in B. hameri and 

 B. evermanni, but strongly unequal in B. krilgeri. The cirri and 

 the external sculpture of the scutum are somewhat similar in B. 

 amaryllis and B. krilgeri. The articulating edges of the radii are 

 smooth in B. Jcriigeri, crenulated in B. amaryllis. By the shape of 

 the tergum B. kriigeri resembles B. cepa Darwin; but the scutum 

 is narrower, the spur of the tergum longer, not so wide; the base is 

 not in the least porous, the aperture is large and the color white. 

 The numerous small teeth of the labrum are a special feature of this 

 species. 



At Albatross station 4935, off Kagoshima Gulf, southern Kiusiu, 

 103 fathoms, a few small specimens were brought up with B. 

 amaryllis. The opercular valves are somewhat wider than in the 

 type, and the adductor ridge of the scutum is more curved (pi. 51, 

 figs. 2-2&). 



B. kriigeri is named for Dr. Paul Kriiger, who has given us sev- 

 eral excellent papers on cirripedes. 



BALANUS TENUIS Hoek. 



1883. Balanus tcnuis HOEK, Challenger Report, vol. 8, Cirripedia, p. 154, pi. 

 13, figs. 29-33 (Challenger Station 204, lat. 12 43' N., long. 122 10' E. ; 

 100 and 115 fathoms). 



1913. Balanus tcnuis HOEK, Cirripedia of the Siboga Expeditie, mono- 

 graphic 31ft, p. 190, pi. 17, figs. 14-19; pi. 18, fig. 1 (Siboga station 105, 

 lat. 6 8' N. ; long. 121 19' E. ; 275 meters). 



