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Besides, it is not at all unlikely that at least some of the specimens from the 
Davis Straits, from the most northern part of Norway (Malangen and Tromsé) and from 
the Murman Sea mentioned under the preceding species, belong to this one. 
REMARKS. This species is sharply distinguished from Ch. mirabile, especially by 
the shape of the frame of the head. It offers an exellent example of the fact that the same 
species of parasite may be found in two different species of hosts; besides, the specimen with 
the eight young females shows very clearly indeed that it is the parasite itself which causes 
the swelling in the carapace of the host, and that it does not — as suggested by Giard and 
Bonnier — lodge itself on or together with a Gyge, or in a swelling formed and afterwards 
left by this parasite. 
VE Mysidion n. gen. 
FEMALE. The body shortly ovate. The head pretty well defined from the trunk, 
but in elderly specimens it is usually found in front on the ventral side of it, as an 
anteriorly and laterally rather well defined eminence; frontal border is wanting, and the skin 
in front and on the sides of the wanting or at most very indistinctly marked lateral border 
is rather thin. The antennule are either fairly short and 2-jointed or almost rudimentary, 
I-jointed. Antenne seem to be wanting. The mouth moderately large, the mouth-border 
narrow, but frequently partly covered with a viscous substance. Maxillulee well developed, 
with a good-sized additional branch (pl. XII, fig. 2a,e’). Maxille powerful; the basal joint 
has at its terminal margin one or two processes, against which the last joint can be folded 
up. The maxillipeds rather short and weak; their basal joint has an irregularly sinuate 
outline; second and third joints fused into one short joint, terminal joint of nearly average 
length, pointed. The trunk is now naked, now in a few places most sparingly provided 
with single hairs of about medium length; trunk-legs and caudal stylets altogether wanting. 
No genital area is found; the genital apertures are placed very far apart at the place where 
the posterior and the lateral outlines meet (pl. XI, fig. 3b); each aperture has — besides 
its usual two lips — its own skeleton consisting of a list which forms a semicircular curve 
(pl. XII, fig. 2b), or the greater part of an oval (pl. XI, fig. 3f), the longitudinal direction 
of which is parallel with the median line of the animal, and whose open side turns 
towards this line (pl. XI, fig.3e); the hindmost lip of the genital aperture is quite close to 
the posterior part of this list, and the muscles radiate forward to its anterior part. The 
entrance (or perhaps rather: entrances) to the odd receptaculum seminis (pl. XI, fig. 3e, 1) is 
or are situated at the median line far in front of the genital apertures; the membrane which 
covers the receptaculum is often closely covered with a great number —as many as twenty 
six — of spermatophores, among which are seen, moreover, stalks of other spermatophores, the 
vesicles of which have disappeared. — The spermatophores (at least in MZys. commume) are some- 
what elongated ovals. — Various parts of the head, as lateral margins, mouth etc., are frequently 
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