196 PERCY SLADEN TRUST EXPEDITION 



900 — frns. 6 Oct. 1905, aa. 2 specimens. Amirante Isles. 750 — fms. 16 Oct. 

 1905, 11. 3 specimens. 16 Oct. 1905, mm. 400 — fms. 2 specimens. 



All the specimens are in very bad condition, and but little better than clear lumps 

 of jelly. 



This species has been very rarely taken near the surface, and it evidently belongs to 

 the mesoplanktonic zone. 



Distribution. Throughout the tropical and sub-tropical regions of all the oceans. 



33. Aglauea hemistoma, Peron et Lesueur, 1809. 



Aglaura hemistoma, Haeckel, 1879, p. 275, Taf. 16, figs. 3 — 4. 



Aglaura hemistoma, Maas, 1893, p. 25, Taf. 1, tigs. 12 — 13. 



Aglaura hemistoma, Vanhoffen, 1902, p. 78. 



Aglaura hemistoma, Lo Bianco, 1904, p. 55, Taf. 34, fig. 138. 



Aglaura hemistoma, Browne, 1906, pp. 176, 184. 



Aglaura hemistoma, Bigelow, 1909, p. 119, pi. 2, fig. 6. 



Aglaura hemistoma, Mayer, 1910, p. 398, pi. 46, tigs. 4—5, pi. 49, figs. 3—7, pi. 50, fig. 11, text-figs. 250—251. 



Aglaura nausicaa, Haeckel, 1879, p. 274, Taf. 16, fig. 1. 



Aglaura hemistoma var. nausicaa, Maas, 1893, p. 26. 



Aglaura hemistoma var. nausicaa, Mayer, 1910, p. 400, fig. 252. 



Aglaura laterna, Haeckel, 1879, p. 274, Taf, 16, fig. 2. 



Aglaura hemistoma var. laterna, Maas, 1893, p. 25, Taf. 1, fig. 14. 



Aglaura hemistoma var. laterna, Mayer, 1910, p. 400, fig. 253. 



Aglaura prismatica, Maas, 1897, p. 24, Taf. 3, figs. 4 — 5. 



Aglaura prismatica, Agassiz and Mayer, 1899, p. 165, pi. 4, fig. 13. 



Aglaura hemistoma var. prismatica, Mayer, 1910, p. 400. 



Aglaura octogona, Bigelow, 1904, p. 257, pi. 2, fig. 9. 



Aglaura hem,istoma var. octogona, Mayer, 1910, p. 401. 



For further synonyms and references see Mayer, 1910, pp. 397 — 401. 



Localities. North of Chagos ; Off Mauritius ; North of Saya de Malha Bank ; 

 Farquhar Group; Alphonse Is.; Amirante Isles. (The collection contained about 120 

 specimens taken at 21 different stations.) 



After the cruise of the " Valdivia" Vanhoffen came to the conclusion that only one 

 species of Aglaura existed. Bigelow on the " Albatross " cruise in the Eastern tropical 

 Pacific paid special attention to Aglaura by examining specimens alive, and he also has 

 decided in favour of a single species. Mayer is of the opinion that only one species exists, 

 but he retains in his monograph the names of the varieties. 



Aglaura hemistoma belongs to the epiplanktonic fauna, and is widely distributed 

 throughout the warm regions of all oceans and seas. In the Biscayan Plankton (Browne, 

 1906) it was most plentiful at about 50 — 100 fms, scarcest at the surface. It did not 

 occur in closing nets below 100 fms. On the " Sealark " expedition Professor Gardiner 

 used the Wolfenden closing-net at only three stations and at each Aglaur'a hemistoTna was 

 taken. It occurred once at 250 fms, and twice at 500 fms. The serial hauls taken with 

 open nets from different depths gave no reliable clue, owing to the paucity of specimens, 

 as to the depth at which the species was most abundant. On each occasion the nets used 

 within 50 fms of the surface contained specimens, and the numerous surface tow-nettings 

 showed that it was not uncommon at the surface. 



