105 
spines are very minute. The antennules are twenty-four-jointed and extend to the end of the 
furca. The long spines on the apex of the free joints of the fifth pair of feet are asymmetrical. 
The spine on the left foot is distinctly thicker than the one on the right. The spines are two 
and one-third times the length of the joint. The small apical spines are equal to one-eighth of 
the length of the long ones. Length of female 4,3 mm. 
The males can easily be separated from the males of the other species, by the minute 
spine on the apex of the rami of the rostrum. The last thoracic segment when viewed from 
above, is seen to be much contracted near the posterior end, then curved outwards and ter- 
minates in conspicuous spines. 
The combined length of the abdomen and furca is contained two and one-third times 
in the total length of the cephalothorax, from the apex of the crest to the base of the genital 
segment. The second segment is longer than the others. 
The antennules are twenty-jointed and extend to the middle of the fourth abdominal 
segment. 
The distal part of the second joint of the basiopodite of the right fifth foot is distinctly 
swollen, and is produced internally into two knob-like processes. The exopodite is one-jointed and 
is slightly forked at the apex. The inner surface of the joint is hollowed out, and is furnished 
with a lamelliform appendage. The endopodite is very short and is pointed at the apex. The 
second joint of the exopodite of the left fifth foot is much longer than the first joint. It is 
furnished with an outer subapical lamelliform process. The proximal part of the inner margin 
bears a strong tooth, and the distal half of the inner margin is furnished with a pad of fine 
spines. The endopodite is of moderate length, and is distinctly forked in the middle into two 
lateral processes. The outer margin of the second joint of the basiopodite bears a large tubercle 
at its proximal end. Length of male 4,75 mm. 
The form recorded by Sars as Scottocalanus acutus, is, according to Farran, identical 
with the female of the above species. 
Scottocalanus securifrons has been recorded from the Gulf of Guinea by my father, 
from the South Atlantic in the vicinity of the Cape of Good Hope by Cleve, and from the 
North Atlantic by Farran, Sars and WotrenpeN. I have also seen males and females that 
were obtained from the plankton collected in the deep water of the Farde Channel. 
2. Scottocalanus persecans (Giesbrecht). Plate XXVII, figs. 10—18. 
Scolectthrix persecans Giesbrecht, 1895, p. 253, pl. III. 
Scolecithrix persecans Giesbrecht & Schmeil, 1898, p. 48. 
Scolecithrix persecans 1. C. Thompson, 1903, p. 20. 
Scolecithrix persecans Cleve, 1904, p. 197. 
Scolecithrix persecans Esterly, 1905, p. 166, fig. 28. 
Scolecithrix persecans van Breemen, 1908, p. 80, fig. 94. 
Four males belonging to this species were found in the plankton collected with the 
HENSEN vertical net at the following stations. 
Stat. 118 (900 metres to surface), I specimen. — Stat. 128 (700 metres to surface), I speci- 
men. — Stat. 148 (1000 metres to surface), 2 specimens. 
105 
SIBOGA-EXPEDITIE XXIX@. 14 
