39 
I regard this species to be more closely related to the one originally illustrated in the 
‘Challenger’ report as -£tzdews armatus, than to the species now known as 4tdeus armatus 
(Boeck). The very strong rostrum described and figured by Brapy, is a character not possessed 
by Borcx’s species. The last thoracic spines in the ‘Challenger’ specimen, appear to have been 
shorter than in the present form, but I have noticed, that these chitinized spines are easily 
damaged, and perfect specimens with the spines complete, may not always be secured. With 
regard to the specimens from the ‘Challenger’ collection examined by Sars, and stated to be 
identical with BorcK’s species: — It is quite possible, that more than one type of “Atzdeus 
was obtained by the ‘Challenger’, but the differences were not regarded as worthy of specific 
-rank at that time, and the type from which Brapy’s figures were drawn, might easily be 
distinct from those examined by Sars. I have found on re-examining the selected specimens 
from the Gulf of Guinea plankton, regarded to be identical with the type described in the 
‘Challenger’ report, that all the three forms now figured were present. £tzdeus giesbrechte, 
and the form now described as 4tzdeus bradyz, proved, on the re-examination of the selected 
specimens, to have been present in the plankton collected by Professor HERDMAN, on the way 
out to Ceylon. 
WOLFENDEN (1903, p. 266) refers to a species, 47%. dradyz (Brady), but I am unable to 
identify it. Brapy has not named a species of “@tdeus after himself. 
Genus Bradyidius Giesbrecht, 1897. 
This genus is closely related to 4¢zdeus, but differs from it in the less highly developed 
rostrum, and by the endopodite of the second pair of swimming feet being distinctly two-jointed. 
One species belonging to this genus was found in the plankton collected during the 
traverse of the ‘Siboga’. The specimens differ in some minor details from Sars figures of the 
northern type but, I have, for the present, decided to regard them as simply tropical examples 
of Bradyidius armatus. 
1. Bradyidius armatus (Brady}j. Plate VI, figs. 1—11. 
Pseudocalanus armatus Brady, 1878, non Boeck 1872, Vol. 1, p. 46, pl. IV. 
Undinopsis bradyz Sars, 1884 (name only). 
Bradyanus armatus Vanhoffen, 1897, p. 322. 
Bradyidius armatus Giesbrecht & Schmeil, 1898, p. 32. 
Bradyidius armatus T. Scott, 1898, p. 264, pl. XII, figs. 1—109. 
Bradyidius armatus T. Scott, 1899, p. 248. 
Lradyidius armatus 1. C. Thompson, 1900, p. 278. 
Lradyidius armatus T. Scott, 1900, p. 383. 
Lradyidius armatus T. Scott, 1901, p. 238. 
Bradyidius armatus T. Scott, 1901 (a), p. 350. 
Undinopsis bradyt Sars, 1902, p. 32, pls. XIX & XX. 
Lradyidius armatus 1. C. Thompson, 1903, p. 16. 
Bradyidius armatus Wolfenden, 1904, p. III. 
Lradyidius armatus Wolfenden, 1905(a@), p. 1005. 
Bradyidius armatus Farran, 1905, p. 31. 
Lradyidius armatus Pearson, 1906, p. 11. 
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