02 



Giesbrecht and Schmeil doubtfully refer the two species described by Brady in the 

 'Challencrer Report', as Etichaeta australis and Euchaeta pulchra, to Undeuchaeta major, but 

 I reo-ard them to be identical with the form described by Giesbrecht as Undeuchacta minor, 

 and more correctly with Lubbock's Undiua plumosa. 



2. Undeuchaeta plumosa (Lubbock). Plate XXII, figs. i — 8. 



Undina plumosa Lubbock, 1856, p. 18, pi. IX, figs. 3 — 5. 



Euchaeta australis Brady, 1883, p. 65, pi. XXI, figs. 5 — 11. 



Euchaeta pulchra Brady (pars) non Lubbock, 1883, p. 63, pi. XIV, figs. 6 — 9. 



Undeuchaeta minor Giesbrecht, 1888, p. 335. 



Undeuchacta minor Giesbrecht, 1893, p 228, pis. 14 & u . 



Euchaeta australis T. Scott, 1893, p. 58, pi. VI, fig. 23. 



Undeuchaeta minor Canu, 1896, p. 424. 



Undeuchaeta minor Giesbrecht & Schmeil, 1898, p. 34. 



Undina plumosa Giesbrecht & Schmeil, 1898, p. 52. 



Undeuchaeta minor Thompson & Scott, 1903, p. 243. 



Undeuchaeta minor Wolfenden, 1904, p. 111. 



Undeucliaeta minor Cleve, 1904, p. 198. 



Undeuchaeta minor Farran, 1905, p. 35. 



Undeucliaeta minor Esterly, 1905, p. 149, fig. 17. 



Undeuchacta australis Sars, 1905 (a), p. 4. 



Undeuchaeta minor Pearson, 1906, p. 15. 



Undeuchaeta minor Sars, 1907 (a), p. 3. 



Undeucliaeta minor Farran, 1908, p. IJ . 



Undeuchacta minor van Breemen, 1908, p. 44, fig. 50. 



This species was well represented in the plankton collected by the 'Siboga'. Thirty-nine 

 females and eleven males were obtained at the following stations. 



Stat. 117', 1 specimen. — Stat. 118 (HENSEN vertical net 900 metres to surface), 3 speci- 

 mens. — Stat. 128 (HENSEN vertical net 700 metres to surface), 5 specimens. — Stat. 141 

 (HENSEN vertical net 1500 metres to surface), 4 specimens. — Stat. 142, 2 specimens. — 

 Stat. 143 (HENSEN vertical net 1000 metres to surface), 6 specimens. — Stat. 189', 1 speci- 

 men. -- Stat. 203 (HENSEN vertical net 1500 metres to surface), 4 specimens. — Stat. 216, 

 1 specimen. — Stat. 230 (HENSEN vertical net 2000 metres to surface), 7 specimens. — 

 Stat. 243 (HENSEN vertical net 1000 metres to surface), 6 specimens. — Stat. 245, 4 speci- 

 mens. — Stat. 276 (HENSEN vertical net 750 metres to surface), 5 specimens. 



The female of Undeuchaeta plumosa is distinguished from Undeuchaeta major, by the 

 absence of any tracé of a median crest on the forehead, and also by the absence of the hooked 

 spine on the ventral surface of the genital segment of the female. 



I think there can be no doubt, after giving careful consideration to Lubbock's description 

 and figures, that the species described in the Transactions of the Zoological Society for 1856, 

 as Undina plumosa, is identical with the male of Euchaeta australis Brady, and represents the 

 missing male of Giesbrecht's Undeuchacta minor. Lubbock's name plumosa ought, therefore, to 

 be adopted as the specific name for this Undeuchacta instead of either australis or minor. 



The species described and figured in the 'Challenger Report' as the female of Etichaeta 



pulchra Lubbock, is really the female of Euchaeta australis which I consider is identical with 



Undeuchaeta minor and to be the true female of Undeuchacta ( Undina) plumosa. Giesbrecht 



62 



