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take to be the mandibular palp. One pair of maxillipeds is present, 
strong, 3-segmented (mp,); the basal segment has a small denticle 
on its anterior margin; the terminal segment is a curved, søomewhat 
compressed claw, obliquely striated laterally. The cephalothorax is 
provided with chitinous thickened lines arranged as in the adult. 
No eyes are visible. Behind the cephalothorax are 3 distinct ab- 
dominal segments and one terminal, representing the postabdomen 
and bearing on each side of the anus a well developed furcal 
appendage with setæ (/). There are two pairs of strong swimming- 
feet, the anterior originating from the ventral margin of the 
Cephalothorax, the second from the first abdominal segment. Each 
foot consists of a strong basal joint and two rami; each: of the 
latter has only one segment with long setæ, provided with delicate 
plumules. Each furcal appendage has 4 setæ, the two inner of 
which, especially the innermost, are long and feathered. 
Upon this "actively fixed” stage A, the Cyclops-stage, follows 
a series of ”fpassively fixed” stages, probably representing as: many 
"Moultings; they may be called ”Pupal stages”, as Claus has done 
in the case of Lernæa branchialis, and Wierzejski with the 
Corresponding stages of the Lernaeid, supposed to be a Pennella. 
They åre more or less clumsy, with the abdominal feet adpressed 
and provided — like the antennules — with more or less clumsy 
setæ or devoid of such, according to the grade of development. The 
antennæ are relatively short and clumsy chelæ, situated below an 
elongated rostrum and evidently not fit for grasping. The fixation 
is brought about by the rostrum; from the end of the latter pro- 
jects an appendage with a terminal dise firmly cemented to the 
skin of the host. This appendage is undoubtedly a hardened secre- 
tion produced by glands in the front end of the cephalothorax; it 
is firm like chitine, resisting like the cuticula itself the action of 
Potash; a pear-shaped swelling marks it off from the rostrum proper. 
I have not been able to see any composition of layers in the. 
Swelling, like those observed by Claus in the pupæ of Lernæa 
"branchialis, where the number of moultings may be judged directly 
