400 
KATHLEEN HADDON. 
which tliey are attached (PI. 22, fig. 7, mf.). All through this 
mass of tissue there is a branching system of lacunge sur- 
rounded by a fairly definite lining of cells ; the main one (ca.) 
runs up the stalk, and dividing into two is continued as a pair 
of lateral spaces in the external body ; these, as mentioned 
above, have thick walls, which are also characteristic of this 
main canal for a short way along the root. 
B. The Male. 
The males are diminutive, and live attached to the female 
in the region of the egg-sacs; there are usually two or three 
to each female, and according to Jensen (6) they fix them- 
selves to the openings of the peculiar glands mentioned before 
as occurring in this region. As, however, these glands are 
only six in number at the most, it is difficult to see how they 
could accommodate the twenty males found by Hansen (3) on 
one female of H. af finis. 
The cephalic segment, whicli occupies about one half of the 
body (PI. 22, fig. 10) has a thoracic segment fused to it, for in 
addition to a pair of three-jointed antennse it bears a pair of 
maxillipeds ; these are four - jointed, the last joint being 
hooked and serving for attachment to the female. There are 
three thoracic segments, each bearing a pair of biramous 
swimming legs ; the first two pairs are alike, each consisting 
of two basal joints, a one-jointed inner ramus and a two- 
jointed outer one, each bearing bristles. The third pair 
resembles the first two except in having a one-jointed outer 
ramus. The abdomen consists of three narrow segments, the 
first two being about equal in size, whilst the third is about 
twice their length and bears a forked telson, each prong 
coni]K)sed of two joints and bearing three stout bristles. 
According to Jensen, howevei-, this chitinous investment is 
merely the last larval skin of the male, the adult being sac- 
like and enclosed, all except the anterior end, in the skin ; the 
anterior end is drawn out and is embedded in the female, being 
kept in position by a rough surface. The two genital openings 
