6i 



of that genus, by the absence of spines or teeth on the inner margin of the first joint of the 

 basiopodite of the fourth pair of feet. The rostrum is one-spined, and the exopodite of the first 

 pair of feet is two-jointed. 



Th ree species, one of which appears to be new, were found in the plankton collected 

 durine the traverse of the 'Sibogfa'. 



i. Undeuchaeta major Giesbrecht. 



Undeuchaeta major Giesbrecht, 1888, p. 335. 



Undeuchaeta major Giesbrecht, 1893, p. 227, pi. 37. 



Undeuchaeta major Giesbrecht & Schmeil, 1898, p. 34. 



Undeuchaeta major I. C. Thompson, 1900, p. 278. 



Scolecithrix cristata I. C. Thompson, 1903 (pars), p. 21, pi. III, male. 



Undeuchaeta major Wolfenden, 1904, p. 111. 



Undeuchaeta major Geve, 1904, p. 19S. 



Undeuchaeta major Farran, 1905, p. 35. 



Undeuchaeta major Esterly, 1905 (pars), p. 148, fig. • 16 (pars). 



Chirundina angulata Sars, 1905 [d], p. 13. 



Undeuchaeta major Pearson, 1906, p. 15. 



Undeuchaeta major Sars, 1907 (a), p. 3. 



Undeuchaeta major Farran, 1908, p. 37. 



Undeuchaeta major van Breemen, 1908 (pars), p. 43, fig. 49 (pars). 



Four specimens, all females, of this Undeuchaeta were found in the plankton collected 



at the following- stations. 



Stat. 117'. — Stat. 141 (HENSEN vertical net 1500 metres to surface). — Stat. 148 (HENSEN 

 vertical net 1000 metres to surface). — - Stat. 230 (HENSEN vertical net 2000 metres to surface). 



The female of this species is distinguished from the others by the presence of a distinct 

 and moderately high crest, by a blunt projection on the right side of the genital segment, and 

 also by the hook on the right side of the genital opening. 



Undeuchaeta major was first described from the Pacific Ocean, but the distribution has 

 since been found to extend to the North Atlantic. 



The 'Siboga' specimens measured 4,8 — 6,4 mm. 



I regard the male of the species recorded by the late I. C. Thompson as Scolecithrix 

 cristata from plankton collected during the cruise of the 'Oceana', to be the male of Undeuchaeta 

 major. It is not the male of Scaphocalanus magnus (T. Scott). I recently had the opportunity 

 of examining a male Copepod taken during one of the cruises of the Scottish International 

 Fisheries Cruiser 'Goldseeker', in the deep water of the Faröe Channel. This Copepod has a 

 similar armature on the fifth pair of feet to that shewn by Thompson (1903 pi. III, fig. 5), 

 and appears to be identical with Undeuchaeta major. The specimen has a median crest and a 

 one-pointed rostrum. 



The form identified and illustrated by Esterly (1905 p. 148, fig. 16), as the male of 



l 'ndeuchacta major, is, I think, very doubtfully so. Esterly gives the length of the female as 



4^ — — mm . and the male as 6 — 6,5 mm. It is very unusual to find the males of the Calanoids 



so much larger than the females. The figure of the left fifth toot resembles that of a species 



of Paraaichacta. 



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