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The samples on vvhich this table is based were taken at Spitzbergen and Greenland, thus
from two places with rather similar external physical conditions.
It must be pointed out here that the figures in this table state only how many
specimens were closely investigated by me. They must, on the other hand, by no means be
considered as Statements of the approximative proportions between the categories of the
table. The samples in question were certainly rather incomplete; they had — if I am
not mistaken — not been collected for quantitative investigations. In addition it may
be mentioned that in some cases only a portion of the individuals found in the samples
were investigated.
Several hundred additional specimens of this species from other samples were investigated.
As, however, these investigations did not give any results beyond what are already shown in
the above table, they were not included in it.
Mature females: In the first column of this table are included such
females as have no eggs in the brood chambers, have very small eggs in the ovaries and have
their natatory bristles on the exopodite of the second antennae broken off. They are specimens
that evidently had recently laid a hatch of eggs. This is shown by the faet that the posterior
parts of their bodies are pressed forward in the same way as in the females in whom the brood
chambers are filled by the voluminous collections of eggs. — In the second column are
included females whose brood chambers are filled with eggs; these eggs are often of rather
different sizes in females of the same sample; the ovaries of these females contain very small
eggs and their second antennae are distinguished by having their natatory bristles broken.
The majority of the sexually mature females often seem to come into this eategory. — The
females of the third column have no eggs in the brood chambers, have eggs in the ovaries
and have the natatory bristles of the second antennae broken off. These females are distinguished
from the females in the first column by not having the backs of their bodies pressed forward
as in the females with their brood chambers filled with eggs. The eggs in the ovaries
of these females are more or less developed, often very small. — The females in the fourth
column are also without eggs in their brood chambers, the posterior parts of their
bodies are not pressed forward as in the females of the two first categories; they have
very small eggs in their ovaries and are characterized by long (unbroken) natatory brist les
on their second antennae.
Mature male s: These were always very rare in the bottom samples of this species
stored in the Swedish State M useu m. They were quite absent from about eighty
per cent of all the bottom samples of this species investigated by me. The same state of affairs
has been observed by the preceding writers, both with regard to this species and other species
of this genus. Thus, for instance, \V. LlLLJEBORG writes with regard to Pli. (Pli.) globosa. 1853.
p. 177, that among a very large number of females he observed only a single male. G. 0. Sars,
1865, pp. 108 and 111 says about this species that while females occur in very great numbers,
males are always extremely rare.
Larvae: Among the specimens of the first and second larval stage that were
investigated by me the females and males were about equal in number.
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