lyS 



COPEPODS OF LAST CRUISE OF CARNEGIE 



p. 83) being a different species, but it has been reported by 

 Farran (1929, p. 255) from the Atlantic and the South 

 Pacific. The lateral margins of the metasome are often in- 

 dented at every joint, giving the body a peculiar nodal ap- 

 pearance. 



Genus CHIRIDIELLA C;. O. Sars, 1907 



Chiridiella species 



Only one of the three species accredited to this genus, all 

 of which occur in the Atlantic, has ever been reported from 

 the Pacific. The three tiny representatives of this genus taken 

 in the vertical tow from 1000 meters at station 64 are too 

 immature to admit identification with the species C. macro- 

 dactyla Sars, which does occur in the Pacific. From the man- 

 ner in which the haul was made, it is impossible to say at 

 which level the specimen was captured between 1000 meters 

 and the surface. 



Genus CHIRIDIUS Giesbrecht, 1892 

 Chiridius poppei Giesbrecht 



[Chiiidius poppei Giesbrecht, Fauna and Flora des Golfes \on 

 Neapel, vol. 19. p. 224, pi. 14, figs. T4-18, 1892.] 



A single female, not fully developed but apparently belong- 

 ing to this species, was taken in the vertical haul from a 

 depth of 1000 meters at station 64 in the southeastern Pacific, 

 also 2 specimens (juvenile males) were found in 50-meter 

 tows off the coast of Japan. It is worthy of note that 5 of the 

 6 specimens obtained in the Siboga plankton were taken in 

 vertical hauls from depths of 700 to 1500 meters. This indi- 

 cates that the species is a deep-water form and not likely to be 

 found in the upper 100 meters except at night. It was re- 

 ported in a surface haul off New Zealand by Farran (1929, 

 p. 255), but the time at which the tow was taken was not 

 given. 



Genus CLAUSOCALANUS Giesbrecht, 1888 



Clausocalanus arcuicornis (Dana) 



[Calauus arcuicornis Dana, Proc. Amer. Acad. Arts and Sci., 

 vol. 2, p. 12, 1849: U. S. Exploring Exped., 1838-1842 

 (Wilkes), vol. 14, pt. 2, Crustacea, p. 1056, 1S53; pi. 72, fig. 

 •ja, b, 1855.] 



Found in all the Atlantic plankton except at the far north, 

 and at practically every locality in the Pacific, often very 

 abundant. It was taken in 29 nocturnal and 76 diurnal sur- 

 face tows, 93 50-meter tows, and 92 loo-meter tows, and in 

 the vertical tow from 1000 meters at station 64. It was also 

 frequently found at all three depths in equal abundance, and 

 was very seldom restricted to a single depth. Such a vertical 

 distribution indicates indifference to light under normal con- 

 ditions, and its horizontal or geographical distribution indi- 

 cates that it is equally indifferent to temperature, except in 

 extremes. It evidently stays at the surface during the night, 

 but is found somewhat more often in the two deeper tows 

 during the day. 



Clausocalanus furcatus (Brady) 



(Figures 27-29) 



\Drepanopns jtircatus Brady, Voyage of H.M.S. Challenger, 

 ZooL, vol. 8, pt. 23, Copepoda, p. 77, pis. 4, 24, 1883.] 



Not found in the Adantic plankton, but abundant in the 

 eastern, southern, and central parts of the Pacific, though not 

 in the western and northern parts. It was present in 22 noc- 

 turnal and 28 diurnal surface tows, 30 50-meter tows, and 

 40 loo-meter tows. Like the preceding species, it was often 

 taken equally at all three depths at the same time. In the 

 Siboga plankton it was found in 24 surface tows, 10 of them 

 at night, and 10 vertical hauls from considerable depths. In 

 the tropics, where the light was strongest, it was often con- 

 fined to the deeper tows. 



Genus CLYTEMNESTRA Dana, 1847 



Clytemnestra rostrata (Brady) 



[Goniopsyllus rostratus Brady, Voyage of H.M.S. Challenger, 

 Zool., vol. 8, pt. 23, Copepoda, p. 107, pi. 42, figs. 9-16, 1883.] 



Found only at station 8 southeast of Iceland in the Atlantic, 

 but scattered irregularly over the entire Pacific and common 

 in the central region. It was taken in 5 nocturnal surface tows, 

 16 50-meter tows, and 28 loo-meter tows. Its absence from 

 the diurnal surface tows shows that it is negative to light, and 

 its presence in the nocturnal surface tows shows that it mi- 

 grates to the surface at night. It is worthy of note that the 5 

 specimens from the Siboga plankton were all captured at or 

 near the surface. 



Clytemnestra scutellata Dana 



{Clytemnestra scutellata Dana, Proc. Amer. Acad. Arts and 

 Sci., vol. I, p. 153, 1847; U. S. Exploring Exped., 1838-1842 

 (Wilkes), vol. 14, pt. 2, Crustacea, p. 1194, 1853; pi. 83, fig. 

 \2a-i, 1855.] 



This species was found at ten of the Atlantic localities and 

 its Pacific distribution was similar to that of the preceding 

 species, but it was somewhat more abundant. It was present 

 in 4 nocturnal and 2 diurnal surface tows, 35 50-meter tows, 

 and 39 loo-meter tows. In view of its comparative abundance 

 in the Carnegie plankton, it seems strange that this species 

 did not appear at all in either the Challenger or the Siboga 

 plankton. Like rostrata, it is negative to light and prefers the 

 two deeper tows during the daytime, but migrates to the sur- 

 face at night. 



Genus CONAEA Giesbrecht, 1891 



Conaea gracilis (Dana) 



\Antaria gracilis Dana, U. S. Exploring Exped., 1838-1S42 

 (Wilkes), vol. 14, pt. 2, Crustacea, p. 1229, 1853; pi. 86, fig. 

 i\a-d, 1855.] 



A few specimens were found in the two deeper tows at 

 station 35 off the Pacific end of the Panama Canal, and this 

 was the only record for the cruise. It is worthy of comment 

 that all the 15 specimens of this species in the Siboga plank- 

 ton were captured in vertical hauls from depths of 700 to 



