95 



by the Swedish South-Polar Expedition belonging to E. similis\ these specimens I compared 

 with the "Siboga" material and found the most perfect agreement excepting in the anomalous 

 vaulting of the frontal plate and the gastric area in the "Siboga" specimens. In the specimens 

 from both sources the antennulae are very characteristic (figs. 2 b and 2 c): the narrow lobe from 

 the first peduncular joint is directed forwards and upwards and is distally bifid with the outer 

 process short and directed a little outwards, the inner process about twice as long and bent 

 somewhat outwards; on the upper side of the second joint the distal inner angle itself is produced 

 as a very short, triangular tooth, while the outer is still less produced; on the third joint lts 

 dorsal carina, seen from the side, occupies somewhat more than the distal half of the upper 

 margin. But in the two largest "Siboga" specimens the frontal plate is a little longer, and 

 the rostral process as much shorter, than in the Swedish specimens; furthermore in the latter 

 specimens the frontal plate and the elevated gastric area have the usual, rather narrow keel, 

 and the frontal plate with rostrum has, seen from the side, the upper margin feebly concave, 

 but in the two largest "Siboga" specimens the frontal plate and a very short part behind it have 

 the upper margin considerably convex, while, seen from above, the upper carina is extremely 

 broad and rounded along the frontal plate and the gastric area (fig. 2 a) ; in the immature male 

 the upper margin of the rostrum is also a little sloping (fig. 2 6), while in the immature female 

 it is bent a little upwards. I am apt to think that this deviating shape is analogous with the 

 curious development of the rostral plate in some Pacific specimens of E. diomedccc, consequently 

 not of specific value (in the small "Siboga" specimen the features described are much less 

 developed), but the question can scarcely be settled with absolute certainty without an examination 

 of the copulatory organs in adult males, and the male in the "Siboga" collection is immature 

 with the processes far from finally developed. Therefore I establish the specimens as a named 

 variety of E. similis. 



Length of the largest "Siboga" specimen, the immature male, 22 mm.; a Swedish 

 specimen measures 31.5 mm. 



Distribution. - The specimen described by Sars is from the South Atlantic, south- 

 east of Buenos Ayres; Ortmann gives it from "Südl. Aquatorialstrom" and from lat. 40°2o'S., 

 long. 7 10' E. 



9. Euphausia tenera H. J. H. PI. XIV, figs. ^a — 30. 



1885. Euphausia gracilis G. O. Sars, Challenger Rep. Vol. XIII, p. 89, PI. XV, figs. 12—23 



(not E. gracilis Dana). 

 1905. Euphausia tenera H. J. Hansen, Buil. Mus. Océan. Monaco, N° 42, p. 9. 



Stat. 66. May 7/8. Bank between islands of Bahuluwang and Tambolungan, south of Saleyer. 



8 — 10 ra. Plankton. 14 specimens. 

 Stat. 75. June 8. Lat. 4°57'.4S., long. H9°2'.8E. 18 m. HEXSEN vertical net, with electric 



light, from 1 1 m. to surface. 2 small specimens. 

 Stat. 1 iS. July 13. Lat. i°38'N., long. I24°28'.2E. Hensen vertical net, from 900 m. to 



surface. 22 specimens. 

 Stat. 12S. July 22. Lat. 4°27'N., long. I25°25'.7 E. 1645111. HENSEN vertical net, from 700 m. 



to surface. 4 specimens. 



