III 
the genus, by the rounded form of the crest when seen from the side, by the shape of the last 
thoracic segment, and by the structure of the fifth pair of feet of both sexes. 
Occurrence. — One female and three males were found in the plankton collected 
with the HeENSEN vertical net at Station 203, 1500 metres to. the surface. 
This species is named in compliment to my father Mr. Tuomas Scort, L.L.D., to whom 
I owe any knowledge I possess in Natural History. His advice and experience have been of 
the greatest value in the preparation of this report. 
7. Scottocalanus helenae (Lubbock). Plate XXVII, figs. 1—9. 
Undina helenae Lubbock, 1856, p. 19, pls. IV & VII. 
Scolecithrix securifrons T. Scott, 1893, p. 47, pl. IV (male). 
Undina helenae Giesbrecht & Schmeil, 1898, p. 52. 
Scolectthrix persecans Farran, 1908, p. 58. 
Male — length 4,9 mm. 
Viewed from above, the body appears elongate and moderately robust. The anterior 
and posterior ends are evenly contracted. The crest is high and conspicuous. The lateral margins 
of the last thoracic segment are much constricted near the distal end, and are produced into 
angularly pointed terminations. Seen from the side, the crest is moderately high and is narrowly 
rounded at the apex. The posterior margin of the last thoracic segment is slightly produced and 
is narrowly rounded, with a considerable slope on each side of the apex. The rostrum is short 
and stout with moderately long apical spines. Their length exceeds the depth of the excavation. 
The antennules are nineteen-jointed and extend to the end of the third abdominal segment. 
The antennae, mandibles, maxillae and maxillipedes are similar to those of the male of 
Scottocalanus securifrons. 
The four pairs of swimming feet are also similar to the four pairs of feet of the male 
of that species. 
The exopodite of the right fifth foot is two-jointed and sickle-shaped. The second joint 
is lamelliform, and is equal to half the length of the first joint. The endopodite extends to 
the distal end of the second joint of the basiopodite. The distal half of the endopodite is 
sickle-shaped, and the outer margin is furnished near the middle ‘with a tooth-like process. The 
joints of the exopodite of the left fifth foot are of about equal length. The proximal end of 
the inner margin of the second joint is considerably dilated. The apex is furnished with two 
curved spines and a pad of hairs. The endopodite is very short and stout. It is only half the 
length of the first joint of the exopodite. 
Female unknown. 
Occurrence. — One specimen of this species was obtained from the plankton col- 
lected with the HENSEN vertical net at Station 148, 1000 metres to the surface. Sod 
This form appears to be identical with the species described and figured by Luspock 
in the Transactions of the Zoological Society for 1856, as Undina helenae. It is identical with 
the male described and illustrated in the report, ‘On Entomostraca from the Gulf of Guinea’, 
as the male of Scolecethrix securcfrons. 
IIl 
