220 



COPEPODA 



70. Scottocalanus securifrons Th. Scott. 

 (PI. VIII figs 13 a — b; text-figs^i a— d, 72 a— e and 73 a- 



d.) 



1893. nee. <3. Scolecithrix securifrons n. sp. Th. Scott pp. 



47—48, pi. IV- V. 

 1896. Scolecithrix securifrons Scott. Canu, p. 425. 

 1898. — Giesbr. & Schmeil, p. 49. 



— Norman, p. 137. 



— J. C. Thompson, pp. 20 — 21. 

 Cleve, p. 197. 



n. sp. Wolfenden, p. 120, pi. IX 

 figs 12 — 15. 



1903. pars. - 

 1903. 

 1904.? 



1904. Lophothrix 



1905. Scottocalanus acutus n. sp. G. O. Sars, p. 7. 

 1906.? pars. — securifrons Scott. Pearson, p. 19. 



1908. — — Farran, p. 57. 



1908. 9 nee. c? Scolecithrix securifrons Scott, v. Bremen, p. 76 



fig. 88. 



1909. Scottocalanus securifrons Scott. A. Scott, pp. 104 — 105 



pi. XXV figs 1—9, pi. XXVIII figs 1—9. 

 191 1. pars. Lophothrix securifrons Scott. Wolfenden, p. 268. 



Size of female from Thor St. 82 was 4-49 mm. ; anterior division (to the end 

 377 mm.; nrosome 072 mm. Th. Scott's specimens measured 4 mm. and 



Description. f<j> 

 of the lateral corners) 

 A. Scott's 4-3 mm. 



The crista is scarcely different from that of the preceding species, but the lateral coruers are 



triangularly produced into spine-like 

 processes, which in dorsal view are 

 seen to be directed somewhat outwards 

 (text-figs 71 a— b). The rostrum has 

 the basal portion elongate, with paral- 

 lel margins; the divergent rami are 

 short, without distinct tooth. The ge- 

 nital somite is strongly swollen below, 

 and it is distally produced into a strong 

 process which overlaps the proximal 

 half of the following somite. Along 

 the hinder margin of somites II — IV 

 a generally well developed serrated 

 seam is observed (text- figs 71 a— b). 

 The antennulae are like those of the preceding species, but the articular membrane between 

 segments 8 cog and 10 are wanting posteriorly, and segments 80^9 have only one sensory seta (text-fig. 

 71 d). The oral appendages are scarcely different from those of the preceding species. 



The natatory legs are very similar to those of the preceding species, but the outer spines of 

 the second basipodite, as well as the inner of the third one, are comparatively longer in the second and 

 third pairs of legs. The second basipodite of the first pair of legs has anteriorly and outwards near 

 the end a rounded broad process; the Se of Re I is comparatively longer. The Se of Re I in the 

 second foot is distinctly pointed. The fifth pair of legs is shorter; the inner process is longer, and its 

 spine is longer and stronger; the outer spine is much shorter, as it does not reach the end of the 

 genital somite, and the inner serration consists of fewer teeth. 



The structure of the labrum etc. is scarcely different from that of the preceding species, 

 fo*. Size of male from Thor St. 82 was 4-98 mm.; anterior division 3-81 mm.; urosome 1*17 mm.; 

 Scott's specimens measured 475 mm. 



Text-fig. 71. Scottocalanus securifrons Th. Scott f9. 



a — b. Abdomen X J 5- c. Genital somite from below X 46. 



d. Segments VII — X of the antennulae. 





