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curved list in advance of the base of the antennula; from the margin, in front of this list, 
runs a transverse series of shorter processes; finally, from the part before the rostrum, 
extending outward and forward up to the anterior margin, we see an area covered with 
some rows of similar processes placed close together. The olfactory seta of the antennule 
extends at least far back on the second abdominal segment. The antennee differ widely from 
those of the four preceding species; they are short, 2-jointed, the first joint is moderately 
long and rather thick, the second joint is only half its length and ends in two set, one 
of which is short, the second a little longer than the first joint. The innermost and foremost 
branch of the maxillule, which e.g. in S. dispar is situated far in front of the three other 
branches, in S. marginata is placed further backward, so as to be nearly at the same height 
as the two branches closest to it, besides being reduced to a short process; the outermost 
branch here is shorter than the two intermediate ones, and seems, moreover, to be naked. 
First jot of the maxille as in the four preceding species, second joint without terminal 
sete, the third one (fig. Gh) serrated, having some very fine acute processes at its inner 
margin. Second joint of the maxillipeds short, third joint exceptionally long, several times 
the length of the second. Abdomen comparatively somewhat smaller than in the nearest 
preceding species, but the mutual dimensions between the segments are the same; the long 
sete of the first segment extend pretty considerably beyond the end of the caudal stylets, 
and the terminal setz of these stylets are more than half the length of the body. 
POST-LARVAL DEVELOPMENT. Unknown. 
HABITAT. The marsupium of Iphinoé trispinosa (Goods.) from Messina. In a 
specimen which had Homocoscelis mediterranea (s. p. 97) in its branchial cavity occurred: 
one female, one male and four ovisacs containing larve. This was the only specimen 
infested with this parasite in the material mentioned more specially above on p. 97. 
REMARKS. The most noteworthy feature in this interesting species is no doubt 
that its maxilla as well as its maxillipeds differ so much in the two sexes, and at the 
same time, in both sexes, especially in the female, deviate widely from these appendages 
in all other hitherto known species, not only of this genus, but of the whole family. 
a. Parasites on Isopoda. 
In three species of Isopoda, all belonging to the group Asellota, [I have discovered 
three species of the genus Spheronella. The females of two of the species show great 
similarity to the normal species of the genus which live on Amphipoda, but the third species 
deviates very considerably from these parasites. The only characters common to the females 
of all three species are: antennz seem to be wanting; the mouth is large with a broad or 
very broad mouth-border, the hairs of which are remarkably thick; the maxillule are well 
developed, with long principal branches and at least very distinct additional branch; the 
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