172 



COPEPODS OF LAST CRUISE OF CARNEGIE 



A single female was found at each of three stations in the 

 eastern Pacific and nowhere else. Six specimens of this 

 species were obtained in the Siboga plankton by vertical 

 hauls from 750 to 1500 meters. This is probably another 

 deep-water species which usually stays below the 100-meter 

 level in the daytime. The caudal rami in this species are 

 much longer than any of the abdominal segments. 



Genus BATHYCALANUS G. O. Sars, 1905 



Bathycalanus rigidus G. O. Sars 



{Bathycalanus rigidus G. O. Sars. Bull. Inst, oceanogr. Monaco, 

 no. 377, p. 2, 1920.] 



Six specimens of this species were found in the two deeper 

 tows at station 118, and this is the only record for the cruise. 

 According to Sars (1925, p. 19), this is a bathypelagic species 

 and is found at considerable depths. It would seem as if it 

 must come to the surface during the night, for otherwise 

 these specimens would not have been found as far up as the 

 50-meter tow in the early forenoon. 



Genus CALANOPIA Dana, 1853 

 Calanopia americana F. Dahl 



(Figure 2) 



[Calanopia americana F. Dahl, Ber. Naturforsch. Geseiisch. 

 Freiburg, n. s., vol. 8, p. 21, pi. i, figs. 23-26, 1894(7.] 



Found in small numbers at three stations in the Caribbean 

 region, at two of the stations in the 50-meter tow and at the 

 third station in the loo-meter tow. In these few instances, 

 therefore, the species was negative to light, but they do not 

 furnish sufficient data for any general conclusion. The speci- 

 mens reported in the Siboga plankton came from Bermuda 

 and, together with those here recorded, will establish the 

 form as pelagic rather than littoral. 



Calanopia elliptica (Dana) 

 (Figure 10) 



[Pontella elliptica Dana, Proc. Amer. Acad. Arts and Sci., vol. 

 2, p. 27, 1849; U. S. Exploring Exped., 1838-1842 (Wilkes), 

 vol. 14, pt. 2, Crustacea, p. 1132, 1853; pi. 79, fig. 6a, b, 1855.] 



A few females were taken at station 32 in the Caribbean, 

 and both sexes were found abundantly near the Samoan 

 Islands in the Pacific. The species was far more abundant in 



the Siboga plankton, where it was found in 32 surface tows, 

 10 of them taken during the night. Since it was captured at 

 the surface here also, we may infer that it is usually positive 

 to light. 



Genus CALANUS Leach, 18 19 



This is one of the oldest and best-known copepod genera, 

 and its species are widely distributed in every ocean and in 

 all zones. One of its species attains the largest number of 

 individuals among the copepods and is known to congregate 

 in countless swarms to the exclusion of all other species. 

 Seven species were present in the Carnegie plankton, three 

 in the northern regions and the other four in the temperate 

 and tropical regions. 



Chart 3. Daytime vertical distribution of species of Ccilaniis: 

 (i) cristatus, (2) finmarchiciis, (3) helgolandiciis, (4) hyper- 

 boreiis, (5) minor, (6) propi/iquus, (7) tonsus. One species, 

 cristatus, was confined to the two lower tows; the other six ap- 

 peared at all three depths, but were more abundant in the deeper 

 tnws than at the surface. This was true e\en of pnmarcbicus, 

 which was the only species that was least abundant at 50 meters. 



Calanus cristatus Kr0yer 



[Calantis cristatus Kr^yer, Voy. comm. sci. Nord. Scandina\'ie 

 ... la corvette "La Recherche," atlas, pi. 41, 1842-45; Natur- 

 hist. Tidsskr., Kjobenhavn, ser. 2, vol. 2, pp. 547, 553, 607, 

 1 848-1849.] 



Found only at the Pacific stations north of latitude 40°, 

 and hence, a boreal species. It was entirely confined to the 

 two deeper tows, which indicates that it is negative to light, 

 and its numbers were small except in the loo-meter tow at 

 station 120. The specimens obtained had every appearance 

 of being immature, since none could be found in which the 

 rami of the fifth legs had more than two segments. The 

 species has been recorded by Van Breemen (1907, p. 10) for 

 the North .\tlantic in the region traversed by the Carnegie, 

 but did not appear in any of the tows taken in the Atlantic 

 during the present cruise. 



Calanus finmarchiciis (Gunner) 



[Monocuhis fiiimarchicus Gunner, Skr. Kjobenhaxnske Selsk., 

 vol. 10, p. 175, figs. 20-23, 1765-] 



Like the preceding species, this well known copepod is a 

 boreal form and except at station 130 was found only above 

 latitude 40° in both oceans. It was present in 11 surface tows, 

 10 50-meter tows, and 13 100-meter tows. The fact that no 

 trace was found of the countless swarms of this species re- 

 ported from the North Atlantic may be due to the season of 

 the year when the Carnegie tows were taken. It is possible 

 that similar swarms might exist in Bering Sea north of the ' 

 Aleutian Islands at the right time of year. The Carnegie 

 records seem to substantiate Russell's (1928) statement that 

 this species is negative to light at medium temperatures, but 

 becomes positive at lower temperatures. 



Calanus helgolandicus (Claus) 



[Cetochihis helgolandicus Claus, Die freilebenden Copepoden, 

 p. 171, pi. 26, figs. 2-9, 1863.] 



This species was abundant over the entire .Vtlantic north 

 of the equator hut was found at only lour stations in the 

 Pacific. It was captured in 4 nocturnal and 16 diurnal surface 

 tows, 18 50-meter tows, and 23 loo-meter tows. It is also 

 often found in about equal abundance at all three depths at 



