35 
of the genital apertures — as in Mysidion — has its own list, which in this animal forms 
a ring (fig. 3i); in the front part of this ring we see a rather large hole (k) which serves 
as opening to a gland (comp. Mysid. abyssorum). The genital aperture (g) lies up to the 
part of the ring which is turned towards the median plane of the animal. Contrary to 
Mysidion, the distance between the rings varies between being a little greater and very 
much smaller than the diameter of each. A long way in front of the genital apertures 
we see two knots a little apart from each other (fig. 3g, r‘, fig. 3e, 0) which show as it 
were irregular cracks in the thick chitine; no doubt they form the entrances to the recep- 
taculum seminis (fig. 3e,r) which is odd, much broader than it is long, and at each side 
bends backward, thus continuing as two almost parallel ducts, which are wide, at the 
middle sowewhat narrowed, and run to the genital apertures. No spermatophores have 
been found. 
b. The Male. 
Out of my forty-three species I know the males of thirty-two, viz. of all species of 
the genera Stenothocheres, Homoeoscelis, Mysidion and Aspidoecia, as well as of twenty-five 
out of the thirty-four species of Spheronella. So in nine species of Spheronella and in the 
two species of Choniostoma the males are still unknown. With respect to the latter genus 
particularly the gap is keenly felt. 
The male is always much smaller than the adult female — as a rule quite dispro- 
portionally so. In three species only: Spher. frontalis, S. decorata and S. curtipes, its length 
exceeds 4/2 mm. The largest male I know belongs to S. cwrtipes and measures ‘92 mm. in 
length and °/s of this size in breadth. In most species the length is about !/4—1/5 mm., and 
the length somewhat exceeds the breadth. The smallest normal males [I have found in 
Aspidoecia Normani, two specimens of which were respectively 147 and -138 mm. long. 
In Mysidion abyssorum the normal male seems to be about -164 mm. long, though I have 
found two perfectly dwarfish specimens, of which one was ‘099 mm. long — and this is one 
of the smallest of adult Copepods hitherto discovered, however, it may be that these two 
specimens were recently hatched and had not grown to their full size (s. below under »post- 
larval development«). The genus Homocoscelis shows least difference between the male and 
the female, especially H. mediterranea, of which the largest female was °31 mm. long, 
32mm. broad and rather flat, whereas the male was 174 mm. long, ‘096 mm. broad and 
equally thick. The greatest difference between the sexes I have found in Spher. microcephala, 
in which the largest female was 144mm. long, of the same breadth and almost. perfectly 
globular, whereas the male without counting the rostrum was ‘18mm. long, 15mm. broad 
and ab. ‘11mm. thick, which gives a volume of between S800—1000 times smaller than 
the female. 
The body, as a rule, is somewhat longer than broad, and seen from below, varying 
from sub-globular to an elongate oval, seen sideways, the back is strongly vaulted, the 
5 
