DISCUSSION OF SPECIES 



185 



stations it was confined to the 50-meter tow and barely 2 or 3 

 specimens were obtained. This is much smaller than the 

 preceding species, and in the male only the left fifth leg is 

 present. In the female the setae of the caudal rami are asym- 

 metrical, being longer and thicker on the right side. 



Genus EUCHAETA Philippi, 1843 

 Euchaeta acuta Giesbrecht 



[Eitcluutc! acuta Giesbrecht, Fauna und Flora des Golfes von 

 Neapel, vol. 19, pp. 246, 262, pi. 16, figs. 6, 10, 14, 18, 21, 27, 

 39; pl- 37. figs- 47. 48, 52. 1892.] 



Not found in Atlantic plankton, and although it was 

 widely scattered in the Pacific there are numerous large gaps 

 in its distribution. It was present in 5 nocturnal and 4 di- 

 urnal surface tows, 25 50-meter tows, and 35 loo-meter tows; 

 also in the vertical tow from 1000 meters at station 64. The 

 left side of the genital segment has an anterior blunt process, 

 which is distinctly notched in dorsal view. 



Euchaeta hebes Giesbrecht 



[Eiic/iafta lubes Giesbrecht, Atti R. Accad. Lincei, Rome, ser. 

 4, vol. 4, sem. 2, p. 337, 1888; Fauna und Flora des Golfes 

 von Neapel, vol. 19, pp. 246, 263, pl. 15, figs. 29, 30; pl. 16, 

 figs. 3-5, 20, 31, 32, 38, 44; pl. 37, figs. 32, 33, 54, 1892.] 



Three specimens of this species were obtained in the 100- 

 meter tow at station 35 off the Pacific end of the Panama 

 Canal, and it was found nowhere else in either ocean. As 

 far as is known, this is the first record of the species from 

 the Pacific Ocean. 



Euchaeta marina (Prestandrea) 



[Cyclops maiiniis Prestandrea, Effemeridi sci. e lett. Sicilia, vol. 

 6, p. 12, 1833.] 



This is the most widely distributed species of the genus, 

 and was found everywhere in both oceans except the north- 

 ern and southern regions of the Pacific (stations 57 to 68 and 

 115 to 129). It was present in 10 nocturnal and 38 diurnal 

 surface tows, 87 50-meter tows, and 82 loo-meter tows. It 

 was often found equally distributed in all three tows at the 

 same time. Both the last thoracic and the genital segment are 

 asymmetrical in the female, the right side being the larger. 



Euchaeta spinosa Giesbrecht 



[Euchaeta spinosa Giesbrecht, Fauna und Flora des Golfes von 

 Neapel, vol. ig, pp. 246, 263, pl. 16, figs. 26, 34, 47; pl. 37, 

 figs- 31. 34, 50, 1892.] 



One specimen was taken in a nocturnal surface tow be- 

 tween stations 63 and 64 in the southeastern Pacific and a 

 few specimens were found in the vertical tow from a depth 

 of 1000 meters at station 64. The former indicates that it 

 does migrate to the surface in the night, and the latter 

 suggests that it remains below 100 meters in the daytime, 

 since it did not appear in the regular tows at station 64. It 

 has been reported by Esterly (1905, p. 159) from the San 

 Diego region, California, by Sharpe (1910, p. 410) from the 

 Cape Cod region on the Atlantic coast, and by other authors 



from the Mediterranean, Atlantic, Pacific, and Indian oceans. 

 In view of such a wide distribution, it is worthy of note that 

 it did not appear in either the Challenger or the Siboga 

 plankton. 



Genus EUCHAETOPSIS? Brady, 1918 



Euchaetopsis? species 



It is with utmost hesitation that two very juvenile copepods 

 from Adantic station i are considered as possibly represent- 

 ing this genus. The genus is monotypic; only the female of 

 Euchaetopsis hastvelli Brady, from the Antarctic Ocean, is 

 known. 



Genus EUCHIRELLA Giesbrecht, 1888 



Euchirella brevis G. O. Sars 



[Enchirclla brevis G. O. Sars, Bull. .Mus. occanogr. Monaco, no. 

 26, p. 12, 1905.] 



Found in the Sargasso and Caribbean regions and scat- 

 tered very irregularly over the entire Pacific with few 

 records at consecutive stations. It was taken in 2 nocturnal 

 and 2 diurnal surface tows, 31 50-meter tows, and 25 100- 

 meter tows. The setae on the enlarged exopod of the 

 second antennae were often exceptionally long, densely 

 plumose, and bright red. These records show the species to 

 be negative to light, with a slight preference for the 50- 

 meter tow. 



Euchirella curticauda Giesbrecht 



[Euchirella curticauda Giesbrecht, Atti R. Accad. Lincei, Rome, 

 ser. 4, vol. 4, sem. 2, p. 336, 1888; Fauna und Flora des Golfes 

 von Neapel, vol. 19, pp. 233, 244, pl. 15, figs. 3, 13, 25; pl. 36, 

 figs. 19, 20, 1892.] 



Found at the first station in the Atlantic and at many 

 stations in the Pacific, long distances apart except in the 

 central region. It was taken in 4 surface tows, 23 50-meter 

 tows, and 11 100-meter tows. The first basipod of the fourth 

 legs has a row of nine to thirteen teeth on its inner margin, 

 and the forehead has a high crest. This species is also nega- 

 tive to light, with more of a preference for the 50-meter 

 tow, and it did not appear in any nocturnal tow. 



Euchirella intermedia With 



[Euchirella intermedia With, Copepoda of the Danish Ingolf- 

 Exped., vol. 3, no. 4, p. 124, 1915.] 



Nine specimens were taken at five Pacific stations, i in 

 the 50-meter tow, 5 in the 100-meter tow, and 3 in the ver- 

 tical tow from 1000 meters at station 64. This species does 

 not have a crest, and there is a single long, slender spine on 

 the posterior surface of the first basipod of the fourth leg. 

 Its entire absence from the surface tows, both nocturnal and 

 diurnal, shows it to be more negative to light than either of 

 the preceding species. 



Euchirella messinensis (Claus) 



[Undina mcssitiensis Claus, Die freilebenden Copepoden, p. 

 187, 1863.1 



This species was not present in the Atlantic plankton, and 

 in the Pacific was found once in a 50-meter tow, once in a 



