DISCUSSION OF SPECIES 



177 



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5 iO 



^100 



if 11 : 11 



Chart 5. Daytime vertical distribution of species of Ccntio- 

 pages: (i) calaniniis, (2) chierchiae, (3) elongatus, (4) jurcatus, 

 (5) hamatus, (6) typicus, (7) violaceus. Two of the species were 

 confined to the surface tow, and one appeared both at the surface 

 and in the lOo-meter tow, but not in the 50-meter tow. Four were 

 present at each of the three depths, one of these being least 

 abundant in the loo-ineter tow and the remaining three least 

 abundant at the surface. 



Centropages calaninus (Dana) 



(Figure 30) 



[Cydopsina calaniiia Dana, Proc. Amer. Acad. Arts and Sci., 

 vol. 2, p. 25, 1849; U. S. Exploring Exped., 1838-1842 

 (Wilkes), vol. 14, pt. 2, Crustacea, pp. 1105, 1106, 1853; pi. 

 78, fig. loa, b, 1855.] 



Not found in the Atlantic plankton, but dispersed over the 

 entire Pacific with two extensive gaps in distribution, one in 

 the southeastern part, the other in the extreme north. It was 

 present in 13 nocturnal and 34 diurnal surface tows, 41 50- 

 nieter tows, and 25 loo-meter tows, and in the vertical tow 

 from 1000 meters, station 64. It was sometimes present 

 equally in each of the three tows at the same time, but was 

 found more often in the two upper tows. More than half the 

 abundance records are expressed in numerals, indicating a 

 paucity in the number of individuals. 



Centropages chierchiae Giesbrecht 



[Centropages chierchiae Giesbrecht, Atti R. Accad. Lincei, 

 Rome, ser. 4, vol. 5, sem. i, p. 81 r, 1889; Fauna und Flora 

 des Golfes von Neapel, vol. 19, pp. 304, 320, pi. 17, figs. 38, 

 39, 45; pi. 18, fig. 5; pi. 38, figs. 3, 7, 1892.] 



Three specimens of this species, including both sexes, were 

 obtained in the surface tow at station 2 near the Sargasso 

 region, and this was the only record for the cruise. This 

 species was originally obtained by Giesbrecht (1892, p. 304) 

 from the Strait of Gibraltar, and has since been reported from 

 the North Atlantic by Cleve (1904, p. 187) and from the 

 Indian Ocean by Thompson and Scott (1903, p. 246). 



Centiopages elongatus Giesbrecht 



{Centropages elongatus Giesbrecht, Zool. Jahrb., Abth. Syst., 

 vol. 9, p. 322, pi. 5, figs. 3-6, 1896.] 



Not present in the Atlantic plankton, but found once in the 

 southeastern Pacific, once in the extreme western part, and at 

 most of the stations between the Hawaiian Islands and 

 Samoa. It was taken in i nocturnal and 4 diurnal surface 

 tows, II 50-meter tows, and 11 loo-meter tows. It was thus 

 largely confined to the two deeper tows, but gave evidence of 

 migration to the surface at night. The appendages of this 

 copepod seem exceptionally brittle; nearly every specimen was 



badly mutilated, though the other copcpods in the same tow 

 were well preserved. 



Centropages furcatus (Dana) 



[Catopia jiircata Dana, Proc. Amer. Acad. Arts and Sci., vol. 2, 

 p. 25, 1849; U. S. Exploring Exped., 1838-1842 (Wilkes), vol. 

 14, pt. 2, Crustacea, p. 1173, 1853; pi. 74, fig. la-d, 1855.] 



Well distributed in the Atlantic except at the extreme 

 north, and in the Pacific confined to the eastern and central 

 parts. It was present in 7 nocturnal and 16 diurnal surface 

 tows, 19 50-meter tows, and 21 lOO-meter tows. It was thus 

 quite evenly divided among the three depths and often ap- 

 peared in them all at the same time. The long caudal rami 

 and the small accessory spines inside the larger ones at the 

 posterior corners of the fifth thoracic segment easily identify 

 the species. 



Centropages hamatus (Lilljeborg) 



[hhthyophorba hamata Lilljeborg, De crustaceis ex ordinibus 

 tribus: Cladocera, Ostracoda et Copepoda, in Scania occur- 

 rentibus, p. 185, pis. 21, 26, 1853.] 



Found at six localities in the Atlantic and at only two in 

 the Pacific, in 4 nocturnal and 4 diurnal surface tows and 2 

 loo-meter tows, but nowhere in a 50-meter tow. Bars in his 

 Crustacea of Norivay (1902, p. 76) said of this species, "It is 

 a true pelagic form, occurring as a rule close to the surface of 

 the sea." And yet he found it common in the fjords and along 

 the whole coast of Norway, and it is one of the species that 

 frequently comes into harbors and estuaries. It is widely dis- 

 tributed in the North Atlantic and occurs in sufficient abun- 

 dance to form an essential factor in the food of certain pelagic 

 fishes. 



Centropages typicus Kr0yer 



[Centropages typicus Kr0yer, Naturhist. Tidsskr., Kj6benha\n, 

 ser. 2, vol. 2, p. 588, pi. 6, 1849.] 



Found only in the surface tow at station 6 in the Atlantic 

 southwest of England, and not at all in the Pacific. Sars in his 

 Crustacea of Nortvay (1902, p. 75) said of this species, "We 

 are justified in regarding it as a true Atlantic form. Off the 

 Norwegian coast it occurs both in the open sea and in the 

 fjords, being often found in considerable abundance at the 

 very surface of the sea." About the same may be said of it 

 along the eastern coast of North America, where it seems to 

 be more of a littoral than a pelagic form, entering most of the 

 harbors and estuaries, and showing a decided preference for 

 the surface. 



Centropages violaceus (Claus) 



[hhthyophorba violacea Claus, Die freilebenden Copepoden, 

 p. 199, pi. 35, figs. 13, 14, 1863.] 



Found in and near the Sargasso region and in the central 

 Pacific about 1000 miles east and southeast of the Hawaiian 

 Islands. It was present in i nocturnal and 3 diurnal surface 

 tows, 9 50-meter tows, and 6 loo-meter tows. It appeared 

 thus chiefly in the two deeper tows, but its presence in the 

 nocturnal tow shows that it migrates to the surface at night. 

 It was not found in either the Challenger or the Siboga 

 plankton, the specimens named violaceus by Brady (1883, 



