DISCUSSION OF SPECIES 



201 



Pacific oFf Tongatabu Island; the present specimens were 

 captured farther west and north, near the Fleming Deep. 



Pandarus sinuatiis Sav 



[I\iiuhinis sinuatiis Sav, Jour. Acad. Nat. Sci. Pliila., vol. i, 

 p. 436, iSiS.] 



A single female was captured in one of the nocturnal sur- 

 face tows taken between stations 35 and 36 in the eastern 

 tropical' Pacific. It was about two-thirds grown and had not 

 yet fastened upon a host, but remained swimming freely 

 with the other plankton copepods. This species is very com- 

 mon along the Atlantic coast of North America, but this is 

 the first record from the Pacific. 



Genus PARACALANUS Boeck, 1865 



Paracalanus aculeatus Giesbrecht 



(Figure loi) 



\ Paracalanus aculeatus Giesbrecht, Atti R. .Accad. Lincei, Rome, 

 ser. 4, vol. 4, sem. 2, p. 332, 1888; Fauna und Flora des 

 Golfes von Neapel, vol. 19, pp. 164, 170,. pi. 9. figs. 20, 26, 30, 

 1892.1 



Not found in the Atlantic plankton, and in the Pacific 

 confined to the southeastern and central parts. It was taken 

 in 3 nocturnal and 5 diurnal surface tows, 14 50-meter tows, 

 and II loo-meter tows. It sometimes remains at the surface, 

 but is more often found in the two deeper tows. The radi- 

 ating setae on the caudal rami are often red in the male. 

 Farran (1929, p. 222) has recorded the species as "frequent 

 in the tropical Atlantic and very abundant at some stations." 



Paracalanus parvus (Claus) 



[Ciihuiiis paii'us Glaus, Die freilebenden Copepoden. p. 173, 

 pi. 26, figs. 10-14, 1863.] 



This small species was very well distributed in both 

 oceans, and approached close to Oithona and Oncaea in 

 abundance. It was taken in 41 nocturnal and loi diurnal 

 surface tows, 128 50-meter tows, and 118 lOO-meter tows. 

 Such vertical distribution indicates that the species is prac- 

 tically indifferent to light, and this conclusion is supported 

 by the fact that it is repeatedly found in equal numbers in 

 each of the three tows at the same time. 



Paracalanus pygmaeus (Claus) 



\Culaniis pygmaeus Claus, Die freilebenden Copepoden. p. 174, 

 1863.] 



Not found in the Atlantic plankton, but widely scattered 

 in the Pacific with numerous long gaps in distribution. It 

 was taken in 10 nocturnal and 11 diurnal surface tows, 26 

 50-meter tows, and 30 loo-meter tows. These records, like 

 those of aculeatus, suggest a species negative to strong light, 

 which comes to the surface at night and stays there in the 

 morning until the light becomes too strong, when it drops 

 to the 50-meter and loo-meter depths. It has been reported 

 from the North and South .Atlantic and the Mediterranean, 

 but this is the first record from the Pacific. 



Genus PAREUCHAETA A. Scott, 1909 



Pareuchaeta grandiremis (Giesbrecht) 



\Euchaeta grandinniis Giesbrecht, Atti R. Accad. Lincei, 

 Rome, ser; 4, vol. 4, sem. 2, p. 337, 18S8; Fauna und Flora 

 des Golfes von Neapel, vol. 19, pp. 246, 264, pi. 16, figs. 11, 

 42; pi. 37, fig. 41, 1892.] 



A few specimens of this species were found in the 100- 

 meter tow at station 24 in the tropical Atlantic, and this was 

 the only record for the cruise. This species was originally 

 obtained by Giesbrecht (1892, p. 246) from the eastern 

 Pacific near the equator from a depth of 1000 meters, and 

 this Carnegie record is the first from the tropical Atlantic. 



Pareuchaeta incisa (G. O. Sars) 



[Euchaeta incisa G. O. Sars, Bull. Mus. oceanogr. Monaco, no. 

 26, p. 17, 1905.] 



Four females of this species were captured in the vertical 

 tow from a depth of 1000 meters at station 64 in the south- 

 eastern Pacific. The species was obtained by Sars (1925, 

 p. 117) from considerable depths in the temperate Atlantic 

 and is probably a deep-water form which does not come 

 above the 100-meter line in the daytime. It has not been 

 recorded except by Sars, and all his specimens came from 

 the temperate Atlantic. 



Pareuchaeta tonsa (Giesbrecht) 



[Euchaeta tonsa Giesbrecht, Bull. Mus. Comp. Z06I., Har\ard 

 Coll., vol. 25, no, 12, Copepoda, p. 251. pi. 4, figs. 9, 10, 

 1895.] 



This species appeared but four times in the Carnegie 

 plankton hauls: twice in the Atlantic at the 50-meter level, at 

 station 11 where it was abundant and at station 12 where a 

 few were found, and twice in the Pacific, where it proved to 

 be very scarce at the levels fished, for here only 3 females 

 were captured, 2 in the loo-meter tow at station 147, and i 

 in the 50-meter tow at station 141. This is apparently a deep- 

 water form that occasionally gets above the lOO-meter line. 

 It may be recognized by the sharp points on either side of 

 the last thoracic segment and by the form of the ventral 

 projection of the genital segment. Sars (1925, p. 122) has 

 recorded thirty-six localities for this species, two of them 

 surface tows, the others vertical hauls from depths of 1000 

 to 5700 meters. 



Pareuchaeta tumidula (G. O. Sars) 



[Euchaeta tumidula G. O. Sars, Bull. Mus. oceanogr. Monaco, 

 no. 26, p. 15, 1905.] 



A single female was taken in the 50-meler tow at station 

 40 in the eastern tropical region of the Pacific. This station 

 was almost on the equator and close to the coast of Ecuador. 

 This is the smallest species of the genus, and has not before 

 been reported from the Pacific. Sars' (1925, p. 119) speci- 

 mens all came from the temperate Atlantic in vertical hauls 

 from 1000 to 3000 meters. 



