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The frontal margin uninterrupted, with scarcely any hairs. The basal joint of the maxillipeds 
moderately stout (fig. 1d), scarcely longer than half the breadth of the head. The genital 
area (fig. le) not nearly twice as long as broad; the whole area between the genital apertures 
and the caudal stylets, a narrow part behind the latter, and an area outside the soft mem- 
brane which borders the genital apertures, are covered with rather short hairs. The 
remainder as in the preceding species. 
MALE. The well-developed specimen illustrated (fig. 1f and fig.1¢) is 17mm. long 
and ‘09mm. broad, thus a little more than half the length of the largest female. The body 
more clumsy than in the preceding species, not twice as long as broad. Frontal margin 
and maxillipeds as in the female. Trunk-legs and caudal stylets shorter, not nearly half 
as long as the breadth of the body, and with very few or no hairs. 
OVISACS. Rather large (fig. 1c), shortly ovate or sub-globular. There may be 
five to twelve, but generally we find six to ten comparatively extremely large eggs in each 
ovisac, and as many as eight ovisacs have been found with one female. 
LARVA. In one ovisac were found larvee nearly on the point of swimming out; 
one of these is figured (fig. 1h); its body is ‘15mm. in length, and the cephalothorax is 
very elongated. The olfactory seta of the antennulz reaches the posterior extremity of the 
cephalothorax. Distance between the maxillz and the maxillipeds considerably shorter than the 
basal joint of the latter. Second abdominal segment scarcely the length of the first. The 
long sete of the caudal stylets considerably shorter than in the preceding species, not half 
the length of the cephalothorax and frequently much shorter. 
POST-LARVAL DEVELOPMENT. Unknown. 
HABITAT. In the branchial cavity of Iphinoé trispinosa (Goods.), at Messina. 
In May and in the beginning of June 1893 I caught fifty-eight specimens in all ages of 
this species in the harbour of Messina, in a depth of ten to twenty fathoms, and seven out of 
these were infested with the parasite. It was only found in specimens which were either 
much more than half-grown or full-grown, so that no parasite appeared on a single one of 
the numerous specimens which were only half-grown or still younger. A female with the 
marsupium containing Spheronella marginata (s. later on), had on its right hand side a 
considerable swelling, in which were two adult females, two males and six ovisacs. In a 
female with less than half-developed marsupium, the left branchial cavity contained a male; 
the right hand side of the carapace, especially its posterior part, bulged very much, and 
under the hindmost part of it were found an adult female, in front of it a male and eight 
ovisacs, the foremost of which was evidently newly laid, whereas another, which was lying 
close up to the female, contained full-grown young ones; this arrangement showed clearly 
that the female had changed place. An adult male contained in its left branchial cavity 
one half-grown female. Another adult male contained, also in its left hand side, one adult 
female, one young female, one male and two ovisacs. The three remaining hosts, viz. a 
male before its last moult and two not quite adult females, have not been dissected, but it 
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