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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 Tromso) 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 Gryge, or in a swelling formed and afterwards 

 left by this parasite. 



V. MySldiOll 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 antennulse are either fairly short and 2-jointed or almost rudimentary, 

 1-jointed. Antennae seem to be wanting. The mouth moderately large, the mouth-border 

 narrow, but frequently partly covered with a viscous substance. Maxillulse well developed, 

 with a good-sized additional branch (pi. XII, fig. 2a, e'). Maxillse 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 (pi. XI, fig. 3 b); each aperture has — besides 

 its usual two lips — its own skeleton consisting of a list which forms a semicircular curve 

 (pi. XII, fig. 2 b), or the greater part of an oval (pi. XI, fig. 3 f), the longitudinal direction 

 of which is parallel with the median line of the animal, and whose open side turns 

 towards this line (pi. XI, fig. 3 e) ; 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 (pi. XI, fig. 3 e, r) 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 Mys. commune) are some- 

 what elongated ovals. — Various parts of the head, as lateral margins, mouth etc., are frequently 



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