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side of the body than in the other genera. The antennulas (fig. la, a and fig. 2g) are of 

 medium length, without distinct articulation, the}' have a few rather short setae, among them 

 one olfactory (fig. le, b). The antennae (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 St. egregius(ng. le, c) probably 3-jointed, with a couple of short terminal setae of 

 unequal length; in St. Sarsii (fig. 2f, c) they are weak, with indistinct articulation. The rostrum 

 is on the whole like that in Sphceronella, though it must be observed that the mouth-border 

 is very narrow. The maxillulae (fig. le, e) are on the whole like those of Sphceronella, the 

 principal branches rather short or of medium length, the additional branch wanting. The maxillae 

 (fig. la, f; fig. le and fig. 2f) are powerful and do not show any important differences from 

 those species of Sphceronella 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 maxilla?, are shorter and slenderer than in most species of Sphceronella, 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. la, 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 setae of unequal length, in the 

 second one (fig. lg, 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 2 a and 2 d 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. lg 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. lg, t), each with four thick setae. The abdomen seen from below (fig. lg and 

 fig. 2i), presents near the outer margins of the basal part two very long genital apertures 

 (g) in their whole or a considerable part of their length; in the abdomen seen sideways 

 (fig. 1 h), 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. lh also shows a receptaculum 

 seminis (r) as a large oblong vesicle, placed a little above the abdomen. I have repeatedly 



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