36o ■ DISCOVERY REPORTS 



January at least. One station taken in this water in March 1933 might perhaps suggest 

 that a spawning may take place later in the season in warmer Weddell Sea water 



(PP- 330-2, 349). 



12. The Rhincalamis population of the Weddell Sea is probably an invasion from an 

 outside area and is carried into the Weddell Sea by warm deep water from the South 

 Atlantic or by the deep current from the South Indian Ocean which flows westwards 

 along the coast of Coats Land south of 66° S. (pp. 330-2, 349-51). 



13. If no spawning at all takes place in the Weddell Sea the adult population found 

 there in the summer must result from the winter spawning in the South Atlantic, and 

 thus be six months old, or from the previous summer's spawning, and thus be a year 

 old (p. 332). 



14. In view of the different ages of the stock of Rhincalamis at different places at the 

 same time of year, it is suggested that spawning takes place in colder Antarctic water 

 later than in warmer water. There is thus a southward movement of the region of spawning 

 from northern warmer water to more southerly colder water as the season advances. At 

 temperatures below the optimum range for the spawning of the species the spawning is 

 delayed. This delay, it is suggested, is the result of retardation of development by reduced 

 temperatures. The parent generation in colder water takes longer to attain maturity and 

 fails to spawn until either the temperature of the water has been raised to within the 

 spawning range by the seasonal southward movement of the isotherms or the population 

 has drifted into water of a suitable temperature for spawning (pp. 354-7). 



15. It is further suggested that temperatures below a certain limit — tentatively placed 

 between o and — i-o° C. — inhibit spawning altogether (p. 355). 



LIST OF LITERATURE 



Ardley, R. a. B. and Mackintosh, N. A., 1936. R.R.S. ' Discovery' II. Discovery Reports (in press). 

 Brady, G. S., 1883. Report on the Copepoda. Report on the Voyage of H. M.S. 'Challenger'. Zoology, viii, 



pt. XXIII, pp. 1-142, text-figs. 1-4, pis. 1-55. 

 1918. Copepoda. Australasian Antarctic Expedition, 1911-14, Sci. Rep., Series C (Zool. and Bot.), 



V, pt. 3, pp. 1-148, 15 pis. 

 Campbell, Mildred H., 1934. The Life History and post-Embryonic Development of the Copepods, Ca.la.nus 



tonsus (Brady) and Euchaeta japonica (Marukawa). J. Biol. Board Canada, I, pp. 1-65, text-figs. 



1-18. 

 CoKER, R. E., 1933 . Arret du developpement chez les Copepodes. Bull. Biol. France Belgique, Lxvii, pp. 276-87, 



text-figs. 1-2. 

 Deacon, G. E. R., 1933. A general account of the Hydrology of the South Atlantic Ocean. Discovery Reports, 



VII, pp. 171-238, text-figs. 1-24, 3 pis. 



1936. The Hydrology of the Southern Ocean. Discovery Reports (in press). 



Farran, G. p., 1927. The Reproduction o/Calanus finmarchicus off the South Coast of Ireland. J. du Conseil, 



II, pp. 132-43, text-figs. 1-2 (Copenhagen). 

 1929. Crustacea. Part X. Copepoda. British Antarctic ('Terra Nova') Expedition. Nat. Hist. Report, 



Zool., VIII, pp. 203-306, text-figs. 1-37, 4 pis. 

 GiESBRECHT, W., 1902. Copepoden. Resultats du Voyage du S.Y. 'Belgica'. Expedition Antarctique Beige, 



pp. 1-49, 13 pis. (Anvers). 



