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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 Tortanus denticulatus. 



Length of 'Siboga' females, 1,6 mm. 



Brady'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 Giesbrecht as 

 Corynura denticulata was taken in the Red Sea. 



2. Tortanus gracilis (Brady). 



Corynura gracilis Brady, 1883, p. 71, pi. XXXIII, figs. 1 — 14. 



Corynura gracilis Giesbrecht, 1893, p. 525. 



Tortanus gracilis Giesbrecht & Schmeil, 1898, p. 258. 



Tortanus gracilis Cleve, 1901, p. 51, pi. VII, figs. 11 — 14. 



Tortanus gracilis Thompson & Scott, 1903, p. 254. 



Tortanus gracilis Cleve, 1903, p. 369. 



Tortanus gracilis Wolfenden, 1905(0), 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. 



Wolfenden has foliowed Cleve in doubtino- the distinction between Tortamis gracilis 

 (Brady), and Tortamis 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 Tortamis forcipatus given by Giesbrecht and that of Tortamis 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. Giesbrecht'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 tracé 

 of spines on the inner margin of the last joint of either foot of the 'Siboga' females of Tor- 

 tanus gracilis. 



I have specimens of Tortanus forcipatus from Patani Bay, Siam. The fifth pair of the 

 female agrees with Giesbrecht'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 Tortamis gracilis obtained during the traverse of the 'Siboga', and also from 

 the plankton collected by Professor Herdman 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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