DISCUSSION OF SPECIES 



203 



1000 meters at station 64 in the southeastern Pacific. It was 

 reported by Farran (1929, p. 260) in a nocturnal surl"ace tow 

 off New Zealand, and hence migrates to the surface at night. 

 In the daytime it probably remains below 100 meters, which 

 accounts for its scarcity in the Carnegie plankton. Steuer 

 (1932, p. 5; 1933, p. 3) recorded this species as abundant in 

 the tropical and temperate Atlantic. 



Genus PONTELLA Dana. 1846 



This genus is widely scattered in both oceans, but with a 

 single exception the localities are far apart and the speci- 

 mens are very few. All the species frequent the surface and 

 are rarely found in either of the deeper tows. They are mod- 

 erately large, with a hook on each lateral margin of the head, 

 a single pair of dorsal eye lenses, and a lens at the base of 

 the rostrum for the ventral eye. They are usually found in 

 temperate and tropical regions, but occasionally farther 

 north or south. 



Chart 14. Daytime vertical distribution of species of Fontcl/ci: 

 (i) atlantica, (2) cristata, (3) danae, (4) lobiancoi, (5) princcps, 

 (6) scctiiifcr, (7) teniiiremis. Four of the species were confined 

 to tlie surface tows, one appeared both at the surface and in the 

 100-meter tow, one was confined to the two upper tows, and one 

 was present at all three depths, but these last two were far more 

 abundant at the surface. This, therefore, may fairly be called a 

 surface genus, the stragglers found in the two deeper tows only 

 emphasizing the greater abundance at the surface. 



Pontella atlantica (H. Milne Edwards) 



[Pontia atUvilica H. Milne Edwards, Hist. nat. Crust., vol. 3, 

 p. 420, pi. 39, 1840.] 



Found at one station (p) in the Caribbean Sea and at 

 four localities in the Pacific. One of the latter was a noc- 

 turnal surface tow, and all the others were diurnal surface 

 tows. It evidently remains consistently at the surface during 

 the entire 24 hours of the day and takes no part in vertical 

 migrations. 



Pontella cristata Kramer 



[Pontella cristata Kramer, Zool. Jahrb., Abth. Syst., vol. 9, 

 p. 721, figs. I, 4-6, 8, 9, 1896.] 



Not found in the Atlantic plankton, but present at four 

 localities in the central Pacific, all the specimens coming 

 from surface tows in the daytime. The species was originally 

 obtained by Kriimer (1896, p. 720) from a little farther south 

 in the Pacific near New South Wales, Australia. As its 

 specific name suggests, it is distinguished by a low crest on 

 the head. 



Pontella danae Giesbrecht 



[Pontella danae Giesbrecht, Atti R. Accad. Lincei, Rome, .ser. 

 4, vol. 5, sem. 2, p. 28, 1889; Fauna und Flora des Golfes von 

 Neapel. vol. 19, pp. ^(n, 477, pi, 24, fig. 40; pi. 40, figs. 16, 

 20, 1S92.] 



Not found in the .Atlantic plankton, and in the Pacific 

 confined to the southeastern part. It was present in i noc- 

 turnal and 5 diurnal surface tows, and i loo-meter tow, but 

 not in any 50-meter tow. The urosome is very asymmetrical, 

 the right caudal ramus is exceptionally enlarged, and the lens 

 of the ventral eye at the base of the rostrum is almost spher- 

 ical. This species has not thus far been reported outside the 

 Pacific Ocean. 



Pontella lobiancoi (Canu) 

 (Figure 94) 



[Pontellina lobiancoi Canu, Bull. sci. France et Belgique, vol. 

 19, p. 102, pis. 8, 9, 1888.] 



Found at three localities in the Atlantic and five in the 

 Pacific. One of the former was a nocturnal surface tow, the 

 others, with one exception, being diurnal surface tows. The 

 exception was a 50-meter tow at station 91, which yielded a 

 larger number of individuals of this species than any other 

 single locality. This would seem to suggest that the species 

 is positive to ordinary light but becomes negative to strong 

 light. 



Pontella pennata Wilson 



[Pontella pennata Wilson, Proc. U. S. Nat. Mus., vol. 80, art. 

 15, p. 27, pi. I, I932ff.] 



A single female was obtained from the surface tow at 

 station i in the Atlantic, and this was the only record for the 

 cruise. Thus far this species has been found only in the 

 North Atlantic not far distant from the American coast. All 

 specimens ever taken were in surface tows, indicating that 

 the species is positive to light. 



Pontella princeps Dana 



[Pontella princcps Dana. Proc. .\mer. .\cad. .^rts and Sci., vol. 

 2, p. 34, 1849; U. S. Exploring Exped., 1858-1842 (Wilkes), 

 vol. 14, pt. 2, Crustacea, p. 1168, 1853; pi. 82, fig. -^a-c, 1855.] 



Not found in the Atlantic plankton, and in the Pacific 

 confined to eight localities in the southeastern region. It was 

 present in 2 nocturnal and 6 iliurnal surface tows and did 

 not appear in either of the two deeper tows. Like atlantica, 

 it apparently remains at the surface both day and night. The 

 left side of the urosome has outgrowths which render it 

 quite asymmetrical. The species has been reported Irom the 

 Indian Ocean and from the tropical Pacific, but has not been 

 found in the Atlantic. 



Pontella securifer Brady 



[Pontella securifer Brady, Voyage of H.M.S. Challenger, Zool., 

 vol. 8, pt. 23, Copepoda, p. 96, pi. 45, 1883.] 



Found at one station (34) in the Caribbean Sea and at five 

 localities in the Pacific, very widely scattered. All the speci- 

 mens were obtained in surface tows, one of which was noc- 



