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Third pair has rami of 8 and 10 segments respectively, which are somewhat more 
elongate than those of the 2™¢ 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 (Pl. 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™4, 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 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 (Pl. 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 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 0.25 X 0.15 mm. 
The specimens were taken at: 
Stat. 257. December 11, 1899. In 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 needles. 
17. Lalanus arcuatus n.sp. Pl. 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 (Pl. 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 
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