2 6 4 DISCOVERY REPORTS 



Typhloscolex mulleri was collected throughout the year in the Antarctic Deep Water, migrating to 

 depth in winter. A few records from the surface layers in summer suggest that at this season this 

 species may also inhabit the Weddell Drift. In the Sub-Antarctic Zone T. mulleri was collected in 

 Antarctic Intermediate Water and Warm Deep Water; and in the Sub-Tropical and Tropical Zones in 

 South Atlantic Central Water, Antarctic Intermediate Water and possibly in Tropical Surface Water. 



Pelagobia longicirrata was collected in all explored water masses of the South Atlantic, except in 

 Sub-Antarctic Surface Water north of 45 S. on the Greenwich Meridian. In the Antarctic and Sub- 

 Antarctic Zones, this species was collected in abundance in summer, from depths of 100 m. to the 

 surface, between the Ice Edge and 45 S., where a minor boundary seems to limit its northerly move- 

 ment. Deacon (1945) has suggested that this boundary separates well-mixed water in the southern 

 half of the Sub-Antarctic Zone from more stably stratified water in the northern half; it may segregate 

 a southern population of Pelagobia longicirrata which inhabits the surface layers for feeding (and/or 

 breeding) purposes. In the Antarctic and Sub-Antarctic Zones, P. longicirrata migrates to depth 

 in winter. 



10. The following species are widespread in distribution, but were never collected in abundance. 

 More collections are required before their distribution can be comprehensively analysed: Maupasia 

 caeca, Travisiopsis coniceps, Lagisca hubrechti. 



11. Circulation. It has been repeatedly found throughout this work that species which occur at 

 depth are limited in their distribution by surface hydrological boundaries. Restriction in range may 

 be maintained by migration between water masses moving in opposite directions. Throughout the 

 Sub-Tropical and Tropical Zones, species which were not collected south of the Sub-Tropical 

 Convergence could remain in this environment by migrating between southerly flowing South 

 Atlantic Central Water, northerly flowing Antarctic Intermediate Water and/or southerly moving 

 Warm Deep Water. Observations on the life histories of these species would help in understanding 

 their distribution. Surface currents throughout these zones set up an anti-clockwise circulation which 

 would also restrict the southerly movement of the species. 



It is probable that most cosmopolitan pelagic polychaetes enter the Antarctic and Sub-Antarctic 

 Zones in the southerly moving Warm Deep Water. Vertical migration in the Antarctic Zone to 

 Antarctic Surface Water together with movement within this layer, until it sinks to form the northerly 

 flowing Antarctic Intermediate Water, would allow these species to circulate throughout the South 

 Atlantic. Within the Antarctic Zone a closed circulation between Antarctic Surface Water and Warm 

 Deep Water is the simplest explanation of zonal movement, but endemic antarctic species and 

 antarctic populations of cosmopolitan species are undoubtedly affected by much more complex 

 circumpolar influences. 



REFERENCES 



Apstein, C, 1891. Die Alciopiden des Naturhistorischen Museums in Hamburg. Jahrb. Hamburg wiss. Anst. VIII, pp. 125-40, 



1 pi. 

 Apstein, C, 1893. Die Alciopiden der Berliner Zoologischen Sammlung. Arch. Naturgesch. lix, pp. 141-50, pi. v. 

 Apstein, C, 1900. Die Alciopiden und Tomopteriden der Plankton-Expedition. Ergebnisse Plankton-Expd. Humbolt-Stiftung. 



Bd. 11, H.b. Kiel and Leipzig, pp. 1-61, pis. and maps i-xiv, text-figs. 1-6. 

 Audouin and Milne-Edwards, 1829, in G. Cuvier, Le Regne Animal. Distribui d'apres son organisation pour servir debase a 



VHistoire Naturelle des Animaux et d 'introduction a Vanatomie comparee. Regne Anim. ed. 2, in, pp. 182-217. 

 Audouin and Milne-Edwards, 1833, in G. Cuvier, Le Regne Animal, xvi, Atlas, pi. 14, fig. 1. 

 Augener, H., 1929. Beitrdge zur Planktonbevolkerung der Weddelhee. Int. Revue d. ges. Hydrob. u. Hydrogr. xxn (5-6), 



PP- 273-312. 

 Augener, H., 1932. Antarktische und Antiboreale Polychaeten nebst einer Hirudinee. Sci. Results Norwegian Antarctic Expd., 



1927-8, Det. Norske Videnskaps Akad. i Oslo, 85 pp., 10 figs. 



