2 IO 



Third pair has rami of 8 and 10 segments respectively, which are somewhat more 

 elongatc than those of the 2 nd cirrus. Pedicels also much longer. 3 or 4 lower segments of 

 longer ramus with a few tooth-like spines disposed along anterior face near distal extremity 

 of segments. 



Fourth pair has also unequal rami of respectively 16, 17 and 20 segments. The lower 

 segments 1 — 7 of the shorter ramus (PI. XX, fig. 20), bear from 2 to 5 curved teeth at the 

 anterior face, those situated near distal extremity being the longest, the others smaller, decreasing in 

 size towards the base of each segment. Most segments, to begin with the 2 nd , bear two to three pairs 

 of spines, two of these pairs close together near distal extremity, and the third at some distance 

 along the anterior margin. Hairs on posterior face of segments disposed at the distal extre- 

 mity, rather long, especially those on the lower segments. Last segment of pedicel without 

 any teeth along anterior face. 



Fifth and sixth cirrus nearly equal, the sixth has one or two segments more in each 

 ramus. In one of the specimens 26 and 30 segments were counted in the 6 th cirrus. Length of 

 segments increases from the basis towards the extremity : the last segments are nearly four times as 

 long as broad. The anterior face of most segments bears three pairs of hairs (PI. XX, fig. 21): 

 the longest near the extremity, the third pair extremely minute about the middle of the anterior 

 face, and the second pair, which is not very long, half-way between the two other pairs. The 

 hairs on the posterior face, near the extremity of the segments, are short in the distal segments, 

 much longer on the basal segments. 



Penis long, much longer than the cirri of the 6 th pair, tapering towards the extremity, 

 uncommonly hairy near and at the extremity. 



Eggs with embryos: Nauplii with black eye-spots, in the mantle cavity. Size of the 

 eggs 0.25X0.15 mm. 



The specimens were taken at: 



Stat. 257. December II, 1899. ^ n Duroa-strait, Kei-islands. Depth down to 52 m. Bottom : coral. 

 A single group of half-a-dozen specimens, most of them overgrown by a sponge- 

 like organism, the surface of which shows numerous short spines or needies. 



17. Balanus arcuatus n. sp. PI. XXI, fig. 4 — 14. 



Shell conical, dirty white, with corroded surface in some, tinged with red and distinctly 

 ribbed in other specimens. Radii broad, with their summits parallel to the basis. Orifice entire, 

 elongately pentagonal. Carino-lateral compartments extremely narrow. Basis flat, not imbedded, 

 not porose. Scutum with the lines of growth crenated ; tergum with the spur broad and confluent 

 with the basi-scutal angle, the apex of the valve distinctly produced and the scutal margin 

 deeply hollowed out. 



Numerous specimens are attached to both surfaces of calcareous plates of a polypoid 

 character, some of them very close together, others at some distance from each other. 

 General shape (PI. XXI, fig. 4) of the shell flatly-conical, with the surface dirty white and 

 more or less corroded in some, and distinctly ribbed and tinged with a more or less vivid red 

 in other specimens. Ribs in that case white or coloured less distinctly, intervals between the 



82 



