i 7 6 DISCOVERY REPORTS 



Remarks. This is one of the most common species of mysid to be found in Antarctic waters. It 

 was taken by the National Antarctic Expedition in 78 25' S., 165 39' E. in 56 fm. It has been recorded 

 by the French, Swedish and Belgian Antarctic Expeditions. In the present collection it was taken 

 in 1 14 hauls (at 78 separate stations), frequently in considerable numbers. Sixty of these stations were 

 situated around the coasts of South Georgia, one to the north of the Falkland Islands, two off the 

 South Sandwich Is., two off the South Orkneys, one between the South Orkneys and South Shetlands, 

 three off the South Shetlands, three in the Palmer Archipelago, two in the Scotia Sea, three in the Bay 

 of Whales and one, very surprisingly, off St Paul de Loanda off the west of Africa in latitude 8° S. 

 This is the only record north of the 46th parallel. 



A. maxima was not taken in large numbers in depths of less than 50 m. or of more than 275 m. — 

 most of the hauls which yielded a large number of specimens being taken between 75 m. and 150 m. 

 In a few cases, specimens were taken in nets which had been fishing at 400 m., but these had failed 

 to close and the animals may have entered the net as it was being hauled to the surface. 



Hansen (19 13, p. 20) recorded A. maxima from waters around South Georgia in May and June. The 

 latest date in the year upon which it was taken by ' Discovery ' was 7 April at station 208 in the South 

 Shetlands, while 'William Scoresby' did not take it later than 7 March at station WS 177 off South 

 Georgia. It was taken at the Marine Biological Station, South Georgia, on four occasions in March 

 and once on 1 May at station MS 32 in East Cumberland Bay, South Georgia. An analysis of the 

 dates in the present collection is given below. 



This species has always been regarded as a purely Antarctic form, but there is some evidence in 

 this collection to indicate that this may be true for the warmer months of the year only. The specimens 

 captured in November included some large adults which were breeding but, although hauls had been 

 taken at all depths earlier in the Antarctic spring in the same localities in which A. maxima abounds 

 later in the year, none were taken. Since it certainly must take some weeks for individuals to grow 

 and become sexually mature and to produce eggs, it would appear that these November adults had 

 been living elsewhere and that migration to the Antarctic occurs during the warmer months of the 

 year. If this is the case it might explain the occurrence of four juvenile specimens at station 274 in 

 August, but it is strange that no records have been made from any intermediate localities. 



A. maxima attains sexual maturity at a much smaller size in warmer waters than in waters at the 

 southern limit of its range. Specimens of less than 35 mm. in length, from station 42 off Cumberland 

 Bay, South Georgia, were mature and breeding, while at station 1644 in the Bay of Whales a specimen 

 of this length was quite immature with very small oostegites. A breeding female from station 1652 

 in the Bay of Whales measured 54 mm. The largest specimens in the collection were two males from 

 station 181 in the Schollaert Channel, Palmer Archipelago measuring 76-5 mm. and 77 mm. respec- 

 tively. These are the largest specimens of the species which have been recorded. 



Analysis of dates 



