side of the body than in the other genera. The antennule (fig. 1a, a and fig.2¢) are of 
medium length, without distinct articulation, they have a few rather short sete, among them 
one olfactory (fig. le, b). The antenne (comp. fig. le and fig. 2f) are placed somewhat 
obliquely outside and in front of the rostrum, but not on its basal part; they are of medium 
length, in Sf. egregius (fig. 1e, ¢) probably 3-jointed, with a couple of short terminal seta of 
unequal length; in S¢. Sarsii (fig. 2f, c) they are weak, with indistinct articulation. The rostrum 
is on the whole like that in Spheronella, though it must be observed that the mouth-border 
is very narrow. The maxillule (fig. Le, e) are on the whole like those of Spheronella, the 
principal branches rather short or of medium length, the additional branch wanting. The maxille 
(fig. la, f; fig. le and fig. 2f) are powerful and do not show any important differences from 
those species of Spheronella which are parasitic on Amphipoda. The same remark can be 
applied to the maxillipeds with regard to their structure, but these limbs, compared with 
the maxillee, ave shorter and slenderer than in most species of Spheronclla, and we may 
add that the second and third joints are always fused into one single comparatively short 
joint, which -at most is a little longer than the pointed terminal joint and lacks the spine 
at the distal inner angle, as the terminal joint lacks a spine inside its apex. 
The trunk is naked all over (so is the whole body with all its appendages). The 
trunk-legs are placed differently from those of the preceding genera; both pairs being 
situated on the ventral side at a good distance within the lateral margin, the first pair 
(fig. la, m) somewhat behind the middle of the body, and the second pair (fig. 1a, n) close 
in front of the basis of the abdomen. Both pairs, though rather small, are very large 
compared with those of the preceding genera. Each leg consists of a peduncle with two 
branches not distinctly set off by articulation, and as a rule the outer branch is the longest. 
In the first pair the outer branch terminates in two strong sete of unequal length, in the 
second one (fig. 1g, u and fig. 2i) each branch apparently consists of two joints, of which 
the terminal one is somewhat spine-like, but it must be preferred to consider each branch 
as being composed of one joint with a long and very thick terminal spine. 
A comparison between the figures 2a and 2d shows that in the same species the 
abdomen may be found more or less distant from the posterior margin on the ventral side 
of the trunk, according as the animal is more or less swelled with eggs. The abdomen is 
not set off from the trunk by an articulation; it consists of a broad, rather stout basal part 
with arched lateral margin (fig. 1g and fig. 2i), and a narrower terminal part with a more 
or less deeply incised extremity, which forms two very short and clumsy, badly defined caudal 
stylets (fig. 1g, t), each with four thick sete. The abdomen seen from below (fig. 1g and 
fig. 2i), presents near the outer margins of the basal part two very long genital apertures 
() in their whole or a considerable part of their length; in the abdomen seen sideways 
(fig. 1h), the genital aperture (g) shows its longest extent, and the muscle which opens it (m) 
is directed towards the dorsal side of the abdomen. Fig. 1h also shows a receptaculum 
seminis (1) as a large oblong vesicle, placed a little above the abdomen. I have repeatedly 
5 
