ms) 
This species appears to be widely distributed in all the oceans. It is evident from Farran’s 
remarks (1908), and its presence in the deep collection at Station 203, although absent at the 
surface, that it occasionally descends to considerable depths. Brapy in his ‘Challenger’ report, 
pointed out the characters of Calanus gracilis, and was of the opinion that future research 
would render necessary the formation of a new genus for this species. 
2. Megacalanus robusteor (Giesbrecht). 
Calanus robustior Giesbrecht, 1888, p. 332. 
Calanus robustior Giesbrecht, 1893, p. 91, pls. 7 & 8. 
Calanus comptus T. Scott, 1893, p. 26, pls. V & VI. 
Calanus robustior Giesbrecht, 1895, p. 248. 
Calanus robustior Giesbrecht & Schmeil, 1898, p. 18. 
Calanus robustior Thompson & Scott, 1903, p. 242. 
Calanus robustior Sars, 1905(a), p. I. 
Calanus robustior Wolfenden, 1905 (a), p. 996, pl. XCVI, figs. 1—6. 
Calanus robustior Esterly, 1905, p. 129, fig. 5. 
This species has a close resemblance to JMegacalanus gracelis and without a careful 
examination may be easily mistaken for it. The robust form of the animal and the very swollen 
genital segment, help to separate it from MJegacalanus gracilis. It was noted at the following 
‘Siboga’ stations but appeared to be rather rare. 
Stat. 37. — Stat. 4o. — Stat. 110. — Stat. 117%. — Stat. 128. — Stat. 141. — Stat. 185. — 
Stat. 189%. — Stat. 245. — Stat. 276. 
The form recorded by my father from the Gulf of Guinea (1893) as ?Calanus comptus 
Dana, and which he was inclined to consider as only a variety of Calanus gracilis, has been 
identified by GrEsBREcHT & SCHMEIL as Calanus robustior, a conclusion that appears to be 
quite correct. 
Megacalanus robustior has been previously recorded from the Atlantic, Pacific, and 
Indian Oceans. 
3. Megacalanus princeps Wolfenden. Plate I, figs. 12—18. 
Megacalanus princeps Wolfenden, 1904, p. 112, pl. IX, fig. 1. 
Macracalanus longicornis Sars, 1905(a), p. 7. 
Megacalanus bradyz Wolfenden, 1905, p. 1, figs. 1—6. 
Megacalanus longicornis Pearson, 1906, p. 6. 
Megacalanus longicornis Farran, 1908, p. 21. 
Megacalanus longicornis van Breemen, 1908, p. 13, fig. 9. 
nec Calanus princeps Brady, 1883, p. 36, pl. IV, figs. 3—7. 
nec Macrocalanus princeps Sars, 1905(a), p. 7- 
nec Megacalanus princeps Wolfenden, 1905, p. 3, pl. I, figs. 7—9. 
nec Megacalanus princeps Pearson, 1906, p. 6. 
nec Lathycalanus maximus Wolfenden, 1906, p. 26, pl. VIII. 
nec Megacalanus princeps Farran, 1908, p. 21. 
nec Megacalanus princeps van Breemen, 1908, p. 13. 
This fine species was represented in the ‘Siboga’ material by five specimens, all females, 
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