io5 



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 linies 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 mal es of the other species, by the minute 

 spine on the apex ot 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 actttus, 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 

 Xorth Atlantic by Farran, Sars, and Wolfenden. I have also seen males and females that 

 were obtained from the plankton collected in the deep water of the Farüe Channel. 



2. Scottocalanus persecans (Giesbrecht). Plate XXVII, figs. 10 — 18. 



Scolecitlirix persecans Giesbrecht, 1895, p. 253, pi. III. 

 Scolecitlirix persecans Giesbrecht & Schmeil, 1898, p. 48. 

 Scolecitlirix per secans I. C. Thompson, 1903, p. 20. 

 Scolecitlirix persecans Cleve, 1904, p. 197. 

 Scolecitlirix per secans Esterly, 1905, p. 166, fig. 28. 

 Scolecitlirix per secans van Breemen, 1908, p. 80, fig. 94. 



Four males belonging to this species were found in the plankton collected with the 

 Hexsen vertical net at the following stations. 



Stat. 118 (900 metres to surface), 1 specimen. — Stat. 128 (700 metres to surface), 1 speci- 

 men. — Stat. 148 (1000 metres to surface), 2 specimens. 



SIBOGA-EXPEDITIE XXIX a. 14 



