386 
PACIFIC SCIENCE, Vol. XXI, July 196/ 
TABLE 5 
Day and Night Depth Distributions for 
Cyphocaris richardi 
DEPTH IN 
METERS 
TOTAL NO. 
SAMPLES 
NO. 
POSITIVE 
SAMPLES 
PER CENT 
POSITIVE 
Night 
500-900 
11 
6 
55 
900-1100 
3 
3 
100 
Day 
500-900 
16 
12 
75 
900-1100 
8 
7 
88 
ing this present study, there is some evidence 
of a vertical movement toward the surface dur- 
ing the dark hours. The report by Stephensen 
and the depth and time records presented by 
Hurley (1956:21-22) support this suggestion. 
Family pronoidae 
Eupronoe minuta Claus 
Eupronoe minuta Stephensen, 1925:160- 
161, figs. 55-56; Chevreux and Fage, 1925: 
425-426, fig. 417; Pirlot, 1929:148-149; Bar- 
nard, K. H., 1930:426; Pirlot, 1930:34-35; 
Barnard, K. H., 1932:289; Shoemaker, 1945: 
245-246; Hurley, 1956:19. 
A total of 322 individuals of this species 
was taken from quantitative samples. It was 
present in 41 trawls ranging in depth from 50 
to 1100 m. Table 6 illustrates the day and night 
depth distributions. Eupronoe minuta was one 
of the two species common at depths of less 
than 100 m during the daylight hours. The 
greatest concentrations of individuals were 
noted from about 50 to 200 m during the day; 
the rest of the population was rather evenly 
distributed throughout the depth range of the 
sampling program. The reason for the appar- 
ent absence of individuals between 400 and 
500 m is not clear. The nighttime depth dis- 
tribution shows an obvious massing of the 
population in the surface waters. Data gath- 
ered with the Foxton closing device indicate 
that the deep, positive, night samples are prob- 
ably the result of contamination from upper 
layers as the net was being lowered and raised. 
This does not exclude the possibility, however, 
that this species may descend during the dark 
hours. 
Family phrosinidae 
Primno macropa Guerin 
Euprimno macropa Stephensen, 1924:143- 
146, chart 22; Pirlot, 1929:130-131; Pirlot, 
1930:22. 
Primno macropa Barnard, K. H., 1930:424- 
425; Barnard, K. H., 1932:287-288; Thor- 
steinson, 1941:93-94, pi. 9, figs. 98-102; 
Mackintosh, 1934:90, fig. 20; Shoemaker, 
1945:234-236; Hurley, 1956:17-18. 
This species occurred in 40 samples ranging 
in depth from 80 to 980 m. A total of 315 
individuals was recovered from aliquots of 
quantitative samples. 
Mackintosh (1934:90) offered data which 
suggest that Primno macropa migrates to the 
surface during the daylight hours and moves 
TABLE 6 
Day and Night Depth Distributions for 
Eupronoe minuta 
DEPTH IN 
METERS 
TOTAL NO. 
SAMPLES 
NO. 
POSITIVE 
SAMPLES 
PER CENT 
POSITIVE 
Night 
0-50 
4 
1 
25 
50-100 
2 
2 
100 
100-200 
7 
4 
57 
200-300 
4 
0 
0 
300-400 
6 
4 
66 
400-500 
2 
0 
0 
500-600 
7 
0 
0 
600-700 
2 
2 
100 
700-800 
1 
0 
0 
800-900 
1 
0 
0 
900-1100 
3 
0 
0 
Day 
0-50 
2 
1 
50 
50-100 
2 
2 
100 
100-200 
2 
2 
100 
200-300 
4 
2 
50 
300-400 
4 
3 
75 
400-500 
5 
0 
0 
500-600 
5 
3 
60 
600-700 
4 
3 
75 
700-800 
3 
2 
66 
800-900 
4 
2 
50 
900-1100 
8 
5 
62 
