DISCUSSION OF SPECIES 



20=; 



Pseudocalanus miiiutus (Kr0ycr) 



[Cdhiiuis inniiittis Kr0ycr, Naturhist. Tidsskr., Kjul)L-nha\ n, 

 ser. 2, vol. 2, p. 543, 1848.] 



This species is easily second in abundance and distribution 

 to Oithona siniilis. It was found, with few exceptions, at 

 every locality in both oceans. It was taken in 42 nocturnal 

 and 88 diurnal surface tows, 116 5o-meter tows, and 106 

 loo-meter tows. It was repeatedly found evenly distributed 

 in all three tows at the same time. It would seem, therefore, 

 that it is more or less indifferent to ordinary light but may 

 become somewhat negative to strong light. 



Genus PSEUDOCHIRELLA G. O. Sars, 1920 



Pseudochirella divaricata (G. O. Sars) 



{Ganlius dirariciita G. O. Sars, Bull. Mus. oceanogr. Monaco, 

 no. 26, p. 10, 1905.] 



A single female was taken in the vertical tow from a 

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

 and this was the only record for the cruise. Since all the 

 specimens thus far obtained have come from considerable 

 depths, this species might possibly have been obtained in 

 other localities if the tows had descended far enough below 

 the lOo-meter level. 



Genus RHINCALANUS Dana, 1853 



Rhincalaniis cornutus Dana 



\Rluiicalaniis cornutus Dana, U. S. E.xploring Exped., 1S38- 

 1S42 (Wilkes), vol. 14, pt. 2, Crustacea, p. 1083, 1S53; pi. 76, 

 fig. in, b, 1855.] 



This species was well dispersed in both oceans, but with 

 several extensive gaps in its distribution. It was taken in 6 

 surface tows, 26 50-meter tows, and 23 loo-meter tows. It is 

 thus negative to strong light, but it may be more or less in- 

 different to weak light and thus linger at the surface in dull 

 weather. 



Rhincalanus nasutus Giesbrecht 

 (Figure 114) 



[Rlinicahiniis misiittis 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. 152, 160, pi. 3, fig. 6; pi. g, 

 figs. 6, 14; pi. 12, figs. 9-12, 14, 16, 17; pi. 35, figs. 46, 47, 

 49. 1892.] 



This species was a trifle less evenly distributed than the 

 preceding one, and there were even more extensive gaps in 

 the Pacific distribution. It was taken in 6 surface tows, 19 

 50-meter tows, and 21 loo-meter tows. It thus bears the same 

 relation to light as cornutus, from which it can be distin- 

 guished by the fact that the rostral filaments are invisible in 

 dorsal view, whereas they can be seen plainly on either side 

 of the head in cornutus. 



Genus SAPPHIRINA J. V. Thompson, 1830 



This genus includes species which are nearly transparent 

 and strongly depressed, with lamellar caudal rami and a pair 



oi eye lenses on the forehead. They were not found in the 

 northern part of either ocean or at the three southern stations 

 in the Pacific. The majority of them show a preference for 

 the two deeper tows, but one manifests a definite preference 

 for the surface and another is about ec]uaUy distributed at 

 all three depths. Several were obtained in such small num- 

 bers as to warrant no conclusions. 



Ch.\rt 15. Vertical distribution of certain species of Supphirinu: 

 (i) angiista, (2) auronitens, (3) darwinii, (4) mctalUna, (5) 

 nigromaculata, (6) opalina, (7) ovatolanccolata, (8) pyrosomatis, 

 (9) salpae. One species was confined to the 50-meter tow and 

 one to the lOO-meter tow. Two others were confined to the two 

 upper tows, and the remaining five appeared at all three depths. 

 One of these latter was most abundant at the surface, one in the 

 roc-meter tow, and three in the 50-meter tow. The species of this 

 genus, therefore, differ nearly as much in their vertical distribu- 

 tion as they do in their specific characters. 



Sapphirina angusta Dana 



[Sapphirina angusta Dana, Proc. Amer. Acad. Arts and Sci., 

 vol. 2, p. 41, 1849; U. S. Exploring Exped., 1838-1842 

 (Wilkes), vol. 14, pt. 2, Crustacea, p. 1240, 1853; pi. 87, fig. 

 3a, b, 1855.] 



About equally distributed in both oceans, with sexeral 

 extensive gaps in the Pacific dispersal. It was present in 5 

 nocturnal and 14 diurnal surface tows, 15 50-meter tows, and 

 13 loo-meter tows. The daytime distribution was thus prac- 

 tically equal at all three depths, and the species manifested 

 no preference for any one of them. Twenty-one of the records 

 were single specimens, and it is worthy of note that all the 

 nine records of this species in the Stbogci plankton were also 

 single specimens. 



Sapphirina auronitens Claus 



[Stipphirina auronitens Claus, Die freilebenden Copepoden, p. 

 153, 1863.] 



This was the most abundant species of the genus, chiefly 

 in the Pacific plankton. It was taken in 16 nocturnal and 55 

 diurnal surface tows, 33 50-meter tows, and 29 loo-meter 

 tows. The species thus shows a preference for the surface, 



