LIST OF LITERATURE 167 



15. The time distribution of larvae and adolescents shows that with advancing de- 

 velopment there is a lengthening of time of occurrence. This is another way of ex- 

 pressing the increasingly indefinite nature of the process of development. The wide 

 range of time within which older forms are found is important ecologically as it ensures 

 a constant supply of food for the whalebone whales in the south. Eggs are found over 

 a period of four and a half months in the earlier part of the southern summer season. 

 Calyptopis and early Furcilia predominate from January onwards and are not found at 

 the beginning of the next summer season. Later Furcilia forms are prominent in the 

 second half of the summer season and a few are found after the winter. Furcilia 6 

 originates, generally speaking, late in the summer season and has an extended period of 

 occurrence carrying it midway into the summer season following hatching. Adolescents 

 have a still more extended period of occurrence, the complete range of which is not 

 within the scope of the present paper (p. 161). 



16. It is postulated that in the light of the information obtained concerning 



(a) Deep distribution of eggs, Nauplii and Metanauplius, 



(b) Diurnal migration of Calyptopis and early Furcilia in warm deep water and 

 Antarctic surface water, 



(c) Persistent occurrence of adolescents at the surface, 



that the continued abundance of E. superba in Antarctic waters and the replenishment 

 of the stock of adolescents at the ice-edge is brought about by the rotary movement 

 resulting from the assemblage of the earlier developmental stages chiefly in the south- 

 ward flowing warm deep water and that of the later stages in the northward flowing 

 Antarctic surface water. This movement is suggested as an alternative to the hypothesis 

 which involves the return of adults to the ice-edge by rotary movements in the surface 

 water alone (p. 163). 



LIST OF LITERATURE CITED 



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 Claus, C, 1863. tjber einige Schisopoden iind niedere Malakosiraken Messinas. 7j. Wiss. Zool., xiii, pp. 422- 



54, pis. xxv-xxix. 

 Damas, D. and Koefoed, E., 1907. Le Plankton de la Mer dii Gronland. Croisiere Oceanographique accom- 



plie a bord de la Belgica dans la Mer du Gronland, pp. 347-427. Brussels. 

 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, pis. viii-x. 



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



Elmhirst, R., 1924. Annual Report, Scottish Marine Biological Association for 1922. 



Frost, W. E., 1935. Larval Stages of the Euphausiids Nematoscelis megalops (G. O. Sars) and Stylocheiron 



longicorne (G. O. Sars) taken off the south-west coast of Ireland. Proc. Roy. Irish Acad., XLii, B, 



No. 16, pp. 443-58, pis. xii-xv. 

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Zool., viii, pp. 37-202, text-figs. 1-78. 

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