Full resolution (JPEG) - On this page / på denna sida - Concluding remarks
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metamorphosis and the later development of its parasite. Very few indeed — if any at
all — of the Parasitic Copepods have been followed up more completely. I therefore
feel somewhat abashed in being unable to settle the systematic position of the new
genus. I have tried in vain, by going through the vast and dispersed literature
concerning Parasitic Copepods, to find any close allies to the Chordeuma. None of the
established families seem to me fit for its reception; evidently therefore it represents
a new family. The obvious idea, that some of the Parasitic Copepods known to infest
Echinoderms might be related to the genus in question, I soon abandoned. The
ectoparasitic Asterocheridae (10) seem widely different; the Pionodesmotes phormosomae
Bonnier (1, 15), producing galls inside the shell of Phormosoma uranus W. Th., and
by its author regarded as the type of a family of its own, does not show any near
affinity, and the same is the case with the “Philichthys amphiurae” Hérouard (12),
hitherto the only Parasitic Copepod found endoparasitic in any Ophiuroid. Neither
seems the structure of Chordeuma to allow an admission into the extremely varied
family Ascidicolidae (2, 3, 4, 5—8), of which at least one member infests an Echinoderm,
the Enterognathus comatulae Giesbr., living in the intestine of Antedon rosaceus (11).
Although some of the most degraded members of this family (f. ex. Enterocola,
Enteropsis, Aplostoma, Ophioseides, Mychophilus) may — the one or the other — show
certain features analogous to those found in Chordeuma f. ex. reduction of antennules,
reduction or loss of the outer branch of the antenna, of the mandibles or maxillulae,
reduction of the thoracic feet, which may become uniramous, of the abdomen etc.,
most of these features only occur in the more or less sessile female, while the male
is adapted to lead a more or less free life; and all the resemblances are certainly
superficial, only due to convergence, while the fundamental structure as well as the
development are very different.
The fundamental conformity of both sexes in Chordeuma, of the body as well as
the appendages — the latter all being uniramous and, except the maxillæ, unsegmented —,
the absence in both sexes of every trace of buccal appendages (mandibles, maxillulæ),
the blindly closed intestinal tract, without any abdominal part, the absence of eyes
in every stage of development, the absence of furcal appendages, and of segmentation
of the rami of the swimming feet in the Cyclops-larva etc. are features which, as far
as I know, do not occur combined in any other Parasitic Copepod.
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