HORIZONTAL DISTRIBUTION, GROWTH AND DYNAMICS OF DISPERSAL 339 



the Sixth FurciHa is clearly dominant and adolescent stages, although proportionately few, are much 

 more frequently encountered than in July. The Fourth and Fifth Furcilias survive but are now becoming 

 scarce. Rarely, however, even in late August, the Fifth Furcilia (Station WS 263) may be encountered as 

 the dominant stage. In September the Sixth Furcilias and adolescents are found in roughly equal propor- 

 tions, the adolescents, however, now slightly preponderating, and the Fifth Furcilia has practically 



LOCALITY 



DATE 



STATION 



ADOL 



FURC 



WW |w m|w e| w m |w e|w m 



10 M \2 13 13 IS 16 16 

 2853 2854 2B57 2365 2859 2863 2372 2864 



WEDDELL EAST 



SOUTH GEORGIA 



IB 19 21 22 22 24 24 27 28 28 28 28 28 29 29 

 2394 2398 2405 2406 2408WS256 2412 WS259WS260WS26IWS262WS263WS264WS266WS267 



Scale per cent 



o so too 



LOCALITY 



DATE 



STATION 



ADOL 



FURC 



LOCALITY 



DATE 

 STATION 



ADOL 



FURC 6 

 5 

 4 

 3 

 2 

 I 



OCTOBER -Second half 



WEDDELL EAST 



WEDDELL MIDDLE 



16 17 18 19 20 21 23 25 26 26 27 28 28 28 29 31 

 453 454 455 459 460 461 462 463 464 465 2465 467 2467 2468 469 2475 



■PTTTTtTTTfTITTT* 



Scale per cent 



nn» 



NOVEMBER- First half 



W m|S G|W E| S G ~ 



471 472 2478 4BI 483 



TIITT 



MONTH 



LOCALITY 



DATE 

 STATION 

 ADOL 

 6 FURC 

 5 

 4 

 3 

 2 

 I 



DATE 



STATION 



ADOL 



FURC 6 

 5 

 4 

 3 

 2 



NOVEMBER- Second halt 



SOUTH GEORGIA 



SOUTH GEORGIA 



15 16 17 17 19 21 22 22 22 23 23 25 26 27 29 7 9 II II 19 I 

 484 487 488 491 494 500WS487WS488 502 503 507 511 517 518 523 * 2513 *- 527 537 539 STATION 



S G W E S G 



LOCALITY 



TTffTTTAT-T 



Scale per cent 



W W . WEDDELL WEST 



WM WEDDELL MIDDLE 



WE WEDDELL EAST SG SOUTH GEORGIA BS BRANSFIELD STRAIT 



* SAMPLE FROM SIGHTED SWARM 



Fig. 95. Developmental condition of larval or mixed larval and adolescent swarms in the surface waters of the 



ice-free Weddell zone in winter and spring. 



disappeared. In Weddell East, however, it appears that the Sixth FurciHa may occasionally be en- 

 countered dominant not only up to the end of September but even into early October (see Stations 2443, 

 2445 and 2447) and this (see below), it seems, may be a phenomenon peculiar to the far eastern reaches 

 of the current. In October and November the swarms are predominantly adolescent. The Sixth Furcilia 

 survives in a varying measure of abundance throughout both months and may occasionally, although 

 rarely, as for example at Stations 2447 and WS 488, be encountered as the dominant stage. It becomes 

 very scarce, however, shortly after the middle of November and by December the last surviving larval 

 stages have for all practical purposes^ outgrown themselves and reached the adolescent state.^ 



1 In Weddell West a single Sixth Furcilia was in fact recorded in the 50-0 m. vertical haul at Station 760 in December 193 1. 

 ^ See, however, p. 338, note i. 



39-2 



