184 



COPEPODS OF LAST CRUISE OF CARNEGIE 



Genus EUAUGAPTILUS G. O. Sars, 1920 



Euaugaptilus filigerus (Claus) 



[Hcmicalaniis filigerus Claus, Die freilebenden Copepodeii, p. 

 179. 1863.] 



A single female was taken in the 100-meter tow at station 

 55, and this was the only specimen for the entire cruise. The 

 5 specimens reported by A. Scott (1909, p. 136) from the 

 Siboga plankton were each captured in a separate vertical 

 tow from a considerable depth. Hence we may reasonably 

 infer that the species is nowhere abundant and that it is a 

 deep-water form which very seldom comes into the upper 

 100 meters. The fact that the two abdominal segments and 

 the caudal rami are of the same length will distinguish the 

 species. 



Genus EUCALANUS Dana, 1853 



The species of this genus were widely scattered in both 

 oceans, but the distribution was markedly gregarious, with 

 teeming colonies separated by long intervals of entire ab- 

 sence from the plankton. The species are dispersed over all 

 the oceans, including the Mediterranean, Arctic, and Ant- 

 arctic, and some of them can be found in every zone, but 

 they are more common in the tropics and southern localities 

 than in the north. They are also present at various depths, 

 from the surface to some of the deepest tows that have 

 been taken. 





Chart 7. Daytime vertical distribution of species of Ettcahvuts: 

 (i) attctiuatiis, (2) crasstis, (3) clongatus, (4) monachus, (5) 

 nnicronatus , (fi) subtenids. A single species was confined to the 

 50-meter tow, and the other five species were each distributed at 

 all three depths but were least abundant at the surface. Three of 

 these five species were most abundant in the 50-meter tow, one 

 was most abundant in the loo-meter tow, and one was equally 

 abundant in the two deeper tows. These records show that each 

 of the species is more or less negative to light and prefers the 

 greater depths in the daytime, one of them not coming to the 

 surface at all. 



Eucalanus attenuatus (Dana) 



[Calanus uttcimatiis Dana, Proc. Amer. Acad. Arts and Sci., 

 vol. 2, p. 18, 1849; U. S. Exploring Exped., 1838-1842 

 (Wilkes), vol. 14, pt. 2, Crustacea, p. 1080, 1853; pi. 75, fig. 

 la-m, 1855.] 



This species was taken once in the Atlantic, and was scat- 

 tered over the entire Pacific, even in the extreme north, but 

 with one very long gap (stations 46 to 67) in its distribution 

 and many sliorter ones. It was present in 14 surface tows, 59 

 50-meter tows, and 48 lOO-metcr lows. In view of such wide 

 distribution, it seems strange that this species was not founii 

 in the plankton of the Siboga expedition. 



Eucalanus crassus Giesbrecht 



[Eucalanus crassus Giesbrecht, Atti R. Accad. Lincei, Rome, 

 ser. 4, vol. 4, sem. 2, p. 333, 1888: Fauna und Flora des 

 Golfes von Neapel, vol. 19, pp. 132, 151, pi. 4, fig. 9; pi. 11, 

 figs. 8, 10, 15, 17, 21, 22, 29, 33, 35, 38; pi. 35, figs. 4, 20, 

 26-28, 1892.] 



Not present in the Atlantic plankton, and showing in the 

 Pacific a similar long gap from station 45 to 68, though 

 present at stations 55, 57, and 64(^)5 and another gap from 

 station 134 to 160. It was taken in 2 nocturnal and 3 diurnal 

 surface tows, 25 50-meter tows, and 22 loo-meter tows, and 

 in the vertical tow from 1000 meters at station 64. It can be 

 identified by the very swollen, almost spherical genital seg- 

 ment. 



Eucalanus elongatiis (Dana) 



[Calanus clongatus Dana, Proc. Amer. Acad. Arts and Sci.. vol. 

 2, p. 18, 1849; U. S. Exploring Exped., 1838-1842 (Wilkes), 

 vol. 14, pt. 2, Crustacea, p. 1079, 1853; pi. 74, fig. 10, 1855.] 



Widely scattered in both oceans but quite straggling both 

 in abundance and in continuity of distribution. It was present 

 in 2 nocturnal and 10 diurnal surface tows, 69 50-meter 

 tows, and 62 100-meter tows, and in the vertical tow from 

 1000 meters at station 64. It is the only species in which the 

 urosome is four-segmented, and often attains a large size. 



Eucalanus monachus Giesbrecht 



[Eucalanus monachus Giesbrecht, Atti R. Accad. Lincei, Rome, 

 ser. 4, vol. 4, sem. 2, p. 333, 1888; Fauna und Flora des Golfes 

 von Neapel, vol. 19, pp. 132, 151, pi. 11, fig. 37; pi. 35, figs. 

 5. 14. 33. 36, 1892.] 

 Not obtained in the Atlantic plankton, common in the 

 eastern tropical Pacific (stations 35 to 47 and 71 to 75), but 

 found only three times elsewhere. It was present in 2 noc- 

 turnal and 6 diurnal surface tows, 17 50-meter tows, and ig 

 iQO-meter tows. It is considerably shorter than the preceding 

 species and the genital segment is wider than long. 



Eucalanus mucronatus Giesbrecht 



[Eucalanus mucronatus Giesbrecht. Atti R. Accad. Lincei, 

 Rome, ser. 4, vol. 4, sem. 2, p. 334, 1888; Fauna und Flora 

 des Golfes von Neapel, vol. 19, pp. 132, 151, pi. 11, figs. 9, 

 26, 34; pi. 35, figs. 15, 35, 38, 1892.] 



Not present in the Atlantic plankton, and in the Pacific 

 virtually limited to the eastern tropical region. It was taken 

 in 2 surface tows, 8 50-meter tows, 8 loo-meter tows, and in 

 the vertical tow from 1000 meters at station 64. It is easily 

 recognized by the hooklike projection on the forehead, but 

 this is sometimes concealed by being telescoped into the head. 



Eucalanus subtenuis Giesbrecht 



[Eucalanus subtenuis Giesbrecht, Atti R. Accad. Lincei, Rome, 

 ser. 4, vol. 4, sem. 2, p. 333, 1888; Fauna und Flora des 

 Golfes von Neapel, vol. 19, pp. 132, 150, pi. 11, figs. 23, 42; 

 pi. 35, figs. 9-1 1, 18, 29, 30, 1892.1 



Not present in the Atlantic plankton, and found at only 

 six widely separated stations in the Pacific. At each of these 



