EUPHAUSIA FRIGID A 215 



differ from one another, the foremost having striations which are not present in the 

 hindermost. The foremost expansion reaches a httle farther forward (i.e. distally) than 

 the hindermost. Between them, on the outer side of the distal end of the proximal 

 process, there is a conspicuous tooth-like projection easy to see with a low magnification ; 

 it is in the position occupied by a very small tooth, which is often difficult to see under a 

 high magnification if the membranous lobes are not so placed as to show it in profile, 

 in E. lucens and E. valletitint. The terminal process is bifid at the extremity. The inner 

 branch may be equal in length to or slightly longer or shorter than the outer; it is 

 divided distally into two unequal lobes, the hinder shorter and smaller than the fore- 

 most. The outer branch is narrower than the inner, triangular or lanceolate in shape. 



Fig. 15. E. frigida. a, front part of carapace and first segment of antennules from above, x 12. 

 b, left antennular peduncle from the side, x 18. 



and its hinder margin is finely serrate (Fig. 30 c 2). The lateral process is sharply curved 

 at the end and carries on the curve a strong tooth ; in the axil of that tooth on the hinder 

 side there is a small or very small projection. 



Over 4200 specimens of E. frigida, apart from larval stages, have been measured. The 

 largest males were 21 mm. long, the largest females 24 mm. In September and October 

 some males and females only 1 1 mm. long, and many slightly larger, were found carrying 

 ripe spermatophores, i.e. were sexually mature. The generation born the preceding 

 season become sexually mature at this time before they are physically mature ; they 

 grow to full size a month or two later. 



The larval stages of E. frigida from the second Calyptopis upwards are described later 

 in this paper. 



Remarks. I am sure that Illig (1930, p. 498) is wrong in his only record of E. frigida, 

 a female from subtropical water off the west coast of South Africa. He records none 

 from the stations made by the ' Valdivia ' in Antarctic water where one would expect that 

 the tow-nets could not fail to take some. E. frigida was in fact obtained there. I was 

 doubtful of Illig's records of E. crystallorophias (1930, p. 500, fig. 182) from, among 

 other localities, deep water far from land in the Antarctic. Through the kindness of 



