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One specimen was obtained from the plankton collected at each of the following ten stations. 
Stat 93. — Stat: 99. — Stat. 110. — Stat. 142. — Stat. 169. — Stat. 174. — Stat. 203 
(HENSEN vertical net, 1500 metres to surface). — Stat. 225. — Stat. 229. — Stat. 315. 
Acartia spinicauda has been recorded from the Chinese Coast, the Arabian Sea, and 
the Malay Archipelago. 
21. Family Torranipar. 
Genus Tortanus Giesbrecht, 1808. 
The members of this genus are readily separated from the other. Calanoids by the 
peculiarly twisted form of the anal segment, and by the very large eye that gives the head, 
when seen from the side, an appearance very similar to some of the Cladocera. 
Four species were found in the plankton collected by the ‘Siboga’. Two of the species 
appear to be undescribed. 
1. Lortanus barbatus (Brady). Plate LV, figs. 16—18. 
Corynura barbata Brady, 1883, p. 71, pl. XXXI, figs. 10—12. 
Corynura denticulata Giesbrecht, 1889, p. 26. 
Corynura denticulata Giesbrecht, 1893, p. 525, pls. 31 & 42. 
Corynura barbata, Giesbrecht, 1893, p. 525. 
Tortanus barbatus Giesbrecht & Schmeil, 1898, p. 158. 
Tortanus denticulatus Giesbrecht & Schmeil, 1898, p. 158. 
Four females belonging to the above species were found in the plankton collected with 
the HeENsEN vertical net at Station 185, 1536 metres to the surface. 
The abdomen is composed of three segments. The anal segment is long and narrow. 
The fifth pair of feet consists of two free joints attached to a basal part. The second free joint 
of the left foot is long and comparatively stout. The middle of the inner margin is furnished 
with a tuft of five curved lamelliform teeth. The second free joint of the right foot is scarcely 
equal to half the length of the second free joint of the left foot. The inner margin has no 
tuft of teeth (Plate LV, fig. 18). 
The difference between Zortanus barbatus and Tortanus denticulatus appears to be so 
very slight that I am inclined to regard the two forms as identical. The tuft of teeth on the 
second free joint of the left foot is more compact than in Zortanus denticulatus. That appears 
to be the only difference, except that Zortanus denticulatus has no whip-like ends to the teeth 
as shewn in Brapy’s figure. The tuft of teeth in the ‘Siboga’ specimens is compact, but the 
ends are not whip-like. 
I have specimens of TZortanus barbatus from plankton collected in Patani Bay, Siam, 
with the whip-like ends of the teeth reaching to midway between the tuft and the distal end 
of the joint. The whole of the teeth in these specimens have whip-like ends. The thin ends 
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