download pdf

86
Occurrence. The species has a distribution along the Norwegian coast
similar to that of 1. ncglecta, and is generally found in company with that species.
It is. however, on the whole, less frequent, though in one locality, at Farder, in
the outermost part of the Ghristiania Fjord, I found it in considerable abundance
among decaying algse, in a depth
of about 20 fathoms.
Distribution. British Isles (Sp. Bate), Kattegat (Meinert).
Fam. 2. Arcturidae.
Characters. Body narrow, scarcely at all depressed, approaching
to a
cylindric form. Coxal plates small, though distinct. Metasome with the segments
more or less consolidated, the last one rather large. Superior antenna} small,
with the flagellum uniarticulate. Inferior antenna? very strongly developed, pedi-
form, the outer joints of the peduncle being much elongated and connected by
geniculated bends, flagellum comparatively short. Oral parts
sembling those in the Idotheidce. The 4 anterior pairs of legs very
on the whole re-
unlike the 3
posterior ones, and not ambulatory, nor strictly prehensile; the 1st pair very
small and closely applied to the oral parts, so as to exhibit more the appearance
of maxillipeds; the 3 succeeding pairs of very feeble structure, and fringed with
long delicate seta1
. The
3 posterior pairs of legs normally developed, and rather
strongly built, diminishing somewhat in length posteriorly. Pleopoda present in
the normal number, the 2 anterior pairs being natatory, with narrow and densely
setifcrons plates, the 3 posterior pairs exclusively branchial; 2nd pair in male
with a long bi-setose stylet appended to the inner plate. Uropoda, as in the Ido-
theidce, valve-like, arching over the lower face of the metasome, and having a small
secondary plate
inside the terminal one. Male much smaller than female.
Remarks. In external appearance, the forms belonging to this family are
very unlike those of the preceding one, and were, indeed, by some of the earlier
authors, widely separated from them, and associated with a very different family,
vi/., the Anthuridas. On a closer examination, however, they are, in fact, found
to show nothing in common with the latter family, except the narrow, cylindric
form of the body, Avhereas they exhibit a close relationship to the Llothc'idw, both
as regards the structure of the oral parts, and that of the metasome. The chief
difference consists in the strong development of the inferior antenna 1
, and in the