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appear to be very flexible and are easily damaged or entirely destroyed. This may account 
for their absence in the ‘Siboga’ specimens and in GIEsBRECHT’s Zortanus denticulatus. 
Length of ‘Siboga’ females, 1,6 mm. 
Brapy’s species was described from a single female found in the plankton collected by 
the ‘Challenger’ in Zebu Harbour, Philippine Islands. The form described by GtrsBrecuT as 
Corynura denticulata was taken in the Red Sea. 
2. Tortanus gracilis (Brady). 
Corynura gracilis Brady, 1883, p. 71, pl. XXXIII, figs. 1—14. 
Corynura gracilis Giesbrecht, 1893, p. 525. 
Tortanus gracilis Giesbrecht & Schmeil, 1898, p. 258. 
Tortanus gracilis Cleve, 1901, p. 51, pl. VII, figs. 11—14. 
Tortanus gracilis Thompson & Scott, 1903, p. 254. 
Tortanus gracilis Cleve, 1903, p. 369. 
Tortanus gracilis Wolfenden, 1905 (a), p. 1026. 
Females and males of this species were obtained from the plankton collected at the 
following stations in the area traversed by the ‘Siboga’. 
Stat. 16. — Stat. 50. — Stat. 66. — Stat. 71. — Stat. 142. — Stat. 213, 42 specimens. 
The female can easily be recognised by the comparatively long abdomen and furcal 
joints, and by the structure of the fifth pair of feet. The fifth pair of the female of this species 
is symmetrical or only very slightly asymmetrical. In some cases the second free joint of the 
left foot is a little longer than the right foot, but this appears to be due to age. The ‘Siboga’ 
females measured 1,52 mm. to 1,68 mm. The fifth pair of the small form is quite symmetrical, 
but in the larger specimens there is a very slight difference between the length of the left 
and right sides. 
Wo LFENDEN has followed CiLeve in doubting the distinction between Zortanus gracilis 
(Brady), and TZortanus forcipatus (Giesbrecht). CLEvE says “Fifth pair of legs nearly symme- 
“trical, still, the left leg slightly longer than the right’. I regard the asymmetry between the 
figure of Zortanus forcipatus given by GiEssrecuT and that of Zortanus gracilis shewn by 
CLEVE, as well as what prevails in the ‘Siboga’ specimens, to be too great to justify any doubt 
regarding the distinctness of the two forms. GiEsprecut’s figure shews the terminal joint of 
the left foot to be twice the length of the terminal joint of the right foot. The inner margin 
of the long joint is comparatively straight and it is fringed with fine spines. There is no trace ) 
of spines on the inner margin of the last joint of either foot of the ‘Siboga’ females of Zor- 
tanus gracilts. 
I have specimens of Zortanus forcipatus from Patani Bay, Siam. The fifth pair of the 
female agrees with GursBrREcuT’s figure, except that there does not appear to be any fine 
spines on the inner margin of the last joint of the left foot. These specimens are quite distinct 
from those of Zortanus gracilis obtained during the traverse of the ‘Siboga’, and also from 
the plankton collected by Professor Herpman in the Gulf of Suez in 1903. | 
This species has been recorded from the Arabian and Red Seas, Indian and Pacific 
Oceans, and from the Malay Archipelago. 
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