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PACIFIC SCIENCE, VoL XIX, October 1965 
tions of the Atlantic and Pacific oceans than in 
the western portions mainly in order to escape 
the zone of low oxygen content. Having stud- 
ied the temperature, salinity, and oxygen con- 
tent, he found that in the eastern portions the 
waters are colder, less saline, and poorer in oxy- 
gen content than at the same level in the west- 
ern portions. Fage listed depths of between 
1500 to 2000 m as the zone where G. gracilis 
normally lives. He pointed out that G. gracilis 
is a true bathypelagic species and not a form 
which lives on the bottom, as was previously 
believed. A study of Table 1, where the depth 
of haul and the bottom depth are given for 
the Scripps collections, also shows this to be 
true. In all stations where G. gracilis was found 
the depth of capture is from 400 to 2600 m 
from the bottom, The average difference be- 
tween the depth of capture and the bottom 
depth for all positive stations of G. gracilis is 
1512 m, a considerable distance from the 
bottom. 
Gnathophausia in gens 
G. ingens, in contrast to the other two spe- 
cies, occurs in greatest numbers above 1000 m. 
The average depth of capture in the Scripps 
1950-53 collections was 1100 m, ranging from 
274 to 3914 m. The majority of specimens 
were found at an average depth of 850 m 
(weighted average). Closing nets on the Dis- 
covery Expedition (Tattersall, 1955) show that 
G. ingens was most common between 600 and 
1500 m, but was also found as deep as 2480- 
2580 m and as shallow as 210-340 m. 
Previous studies have shown that the younger 
individuals of this species (less than 80 mm 
in length) are found at more shallow levels 
than are the larger, sexually mature adults. This 
is also generally true of the specimens from the 
Scripps collections. Fage (1941) has found 
that the peculiarities in vertical distribution, 
i.e., in certain areas of the Indian Ocean where 
young individuals were captured at considera- 
bly greater depths, can be explained by the 
vertical distribution of temperatures in those 
regions. He has found that the depth of occur- 
rence of young individuals of less than 80 mm 
length corresponds to depths where the 5°- 
8°C temperature range occurs. When this tem- 
perature occurs deeper, the young individuals 
occur deeper. He also states that in all the 
oceans no individual of a size greater than 80 
mm has been taken with less than 1000 m of 
cable immersed, equivalent to an actual depth 
of 500-600 m. This is generally true of the 
1950-53 Scripps collections, with the exception 
of 2 specimens of 81 and 87 mm body length 
from Stations H51-75 and H51-76, both taken 
at a depth of 366 m. 
Although only 2 (or 8.7%) of the 23 indi- 
viduals of G. ingens of greater than 100 mm 
size were taken at less than 600 m (Sta. H51- 
85), 17 (or 74.9%) of the specimens were 
from depths less than 1000 m (Table 2). 
Fage (1941) states that individuals of G. 
ingens exceeding 80 mm in length are very rare 
and account for 18% among the captures of the 
Dana in the Atlantic, for 13% in the Indian 
Ocean, and only 7% in the Pacific. From the 
Scripps collections in the eastern Pacific I have 
found that 26.5% of the individuals were 
greater than 80 mm in body length. This in- 
crease over Fage’s figures serves to point out 
the improved sampling ability of the mid- 
water trawl in deep waters over traditional 
pelagic nets. Larger and faster swimming speci- 
mens are less able to evade capture or to swim 
out of the nets, due to the greater speed and 
efficiency of the midwater trawl. 
PARASITES 
Fage (1936, 1940, and 1941) has described 
a curious protozoan parasite, Amallocystis fasci- 
atus (an ellobiopsid flagellate), which occurs 
occasionally in specimens of Gnathophausia 
(Fig. 14). Of the 1,051 specimens examined 
from the Dana Expedition, 5 individuals were 
found which contained this parasite: 3 G. zoea 
and 2 G. ingens. 
Of the 400 individuals of the genus Gnatho- 
phausia which I examined from the Scripps 
collections, I found only 3 parasitized speci- 
mens: 2 G. ingens and 1 G. gracilis. No pre- 
vious record of parasitism by this flagellate 
has been reported in G. gracilis. This parasit- 
