190 



COPEPODS OF LAST CRUISE OF CARNEGIE 



in this one deep tow. It has been reported by Cleve (1904, 

 p. 191) from the South Atlantic, but Giesbrecht's (1898, 

 p. 116) record from the North Atlantic can hardly be ac- 

 cepted. 



Heterorhabdus compacius G. O. Sars 



[Heterorhabdtis compactiis G. O. Sars, Res. camp. sci. Albert 

 de Monaco, no. 69, p. 226, 1925; pi. 62, figs. 1-8, 1924.] 



A single female of this species was captured in the vertical 

 tow from 1000 meters at station 64. Farran (1929, p. 267) 

 has recorded this species from two deep vertical tows in the 

 Antarctic south of the Pacific. This deep tow at station 64 

 came out of the Peruvian or Antarctic current, where the 

 temperature was only 3?8 C at lopo meters depth. All the 

 specimens obtained by Sars (1925, p. 226) were taken in 

 vertical hauls from depths of 1500 to 4000 meters. 



Heterorhabdus norvegicus (Boeck) 



[Heteiochaeta noivcgica Boeck, Forhandl. Vidensk. Selsk. 

 Christiania, vol. 14, p. 40, 1872.] 



Not present in the Pacific plankton; a few specimens, in- 

 cluding both sexes, were taken in the 50-meter tow at station 

 II in the North Atlantic. It was recorded by Sars (1900, 

 p. 79; 1902, p. 118; 1925, p. 226) from Nansen's polar ex- 

 pedition and from Greenland, and is evidently a boreal 

 species. In the open ocean it would probably stay well below 

 100 meters and hence escape the Carnegie tows. This is one 

 of the largest species of the genus, and its size aids materially 

 in its identification. 



Heterorhabdus papilliger (Claus) 

 (Figure 56) 



[Heteroclmcta pupi/ligcia Claus, Die freiiebenden Copepodeii, 

 p. 182, pi. 32, 1863.] 



This is the most abundant species of the genus; it was 

 found at three of the Atlantic stations and in all the regions 

 of the Pacific, except far north. But a large majority (46) of 

 the abundance records were numerals, hence it was nowhere 

 at all common. It was present in 4 diurnal surface tows, 15 

 50-meter tows, and 42 loo-meter tows, and i specimen in the 

 vertical tow from 1000 meters at station 64. It is probably 

 negative to strong light. It was also taken in one of the noc- 

 turnal surface tows, and therefore sometimes migrates to the 

 surface at night. The blunt papilla on the forehead and the 

 fifth legs of the male are distinguishing characters. Farran 

 (1929, p. 265) said this was the most frequent species of the 

 genus in the Terra Nova plankton. 



Heterorhabdus spinifrons (Claus) 



[Hetcrochaeta spinijroits Claus, Die freiiebenden Copepoden, 

 p. 183, pi. 32, 1863.] 



This species was second in abundance; it was not present 

 in the Atlantic plankton and was most frequent in the 

 southeastern and central regions of the Pacific. It was taken 

 in 6 50-meter tows and 18 100-meter tows, but did not 

 appear at the surface. The papilla on the forehead is pro- 

 duced into a sharp point or spine, which distinguishes it 

 from the other species. This is another of the larger species, 



and was taken at the surface off New Zeal 

 em Pacific by the Terra Nova expedition. 



the 



ath- 



Genus HETEROSTYLITES G. O. Sars, 1920 



Heterostylites longicornis (Giesbrecht) 



[Hetcrochaeta longicornis Giesbrecht, Atti R. Accad. Lincei, 

 Rome, ser. 4, vol. 5, sem. i, p. 812, 1889; Fauna und Flora 

 des Golfes von Neapel, vol. 19, pp. 373, 383, pi. 19, fig. 7; 

 pi. 20, figs. 14, 21, 25, 26; pi. 39, fig. 44, 1892.] 



This species was not present in the Atlantic plankton and 

 was found but once (station 132) outside the southeastern 

 Pacific. A solitary specimen was taken in a 50-meter tow; all 

 the others were taken in loo-meter tows, except i specimen 

 in the vertical tow from 1000 meters, station 64, hence the 

 species is negative to light. The first antennae reach eight 

 or ten segments beyond the tips of the caudal rami and thus 

 identify the species. The species has been reported from the 

 temperate and tropical Atlantic by Giesbrecht (1898, p. 116) 

 and Sars (1925, p. 238). 



Genus LABIDOCERA Lubbock, 1853 



This is a tropical and temperate genus, and was not found 

 north of latitude 50° north in the Atlantic or 40° in the 

 Pacific, nor south of latitude 35° south in the Pacific. It is 

 also a surface genus, and all the species were found either 

 entirely or almost entirely in the surface tow. The species 

 detruncata was the only one at all widely distributed, all the 

 others being very local in occurrence. 



Chart 10. Daytime vertical distribution of species of Lahi- 

 docera: (i) acuta, (2) aciitijrons, (3) detruncata, (4) nerii, (5) 

 wollastoni. Two of the species were confined to the surface; tlie 

 other three appeared at all three depths but were much more 

 abundant at the surface. This diversity in vertical distribution 

 leads to the conclusion that the positive phototropism of species i 

 and 5 is considerably stronger than that of the other three species. 

 In these three species, furthermore, the difference in phototropism 

 is greater in the upper 50 meters than it is between 50 and 100 

 meters. Attention should be called, however, to the fact that the 

 labidoceran plankton at the surface usually contained a large 

 number of developmental stages, whose reaction to light might 

 change materially on reaching maturity. 



Labidocera acuta (Dana) 



(Figure 51) 

 \PontiUa acuta Dana, Proc. Amer. Acad. Arts and Sci., vol. 2, 



p. 30, 1S49.] 

 [Pontcllina acuta Dana, U. S. Exploring Exped., 1838-1S42 

 (Wilkes), vol. 14, pt. 2, Crustacea, pp. 1150-1152, 1853; pi. 

 80, fig. I2a-c, 1855.] 

 Not present in the Atlantic plankton, although it was re- 

 ported from both the North and South Atlantic by CJies- 



