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of legs, or the gnathopoda, into strong cheliform organs, a character not found in
any other Isopoda, and somewhat recalling the higher Crustacea, crabs and
lobsters. It is indeed from this character that the name of the group, chelifera,
proposed by the author, has been derived. Another very anomalous feature is
the complete fusion of the chephalon and the 1st segment of the mesosome, to form
a kind of carapace, and the localisation of the respiration to that part, instead
of. as in other Isopoda, to the metasome. In connection therewith is also the
more anterior situation of the heart in the present forms. The group contains
2 distinct families, Apseudidce and Tanaidoe, both represented in the fauna
of Norway.
Fam. 1. Apseudidae.
Body more or less elongated, tapering behind, and subdepressed in front,
with the cephalosome rather broad and carinated laterally. Free segments of
mesosome very sharply marked off, and exhibiting at the insertions of the legs,
distinct, though small coxal plates. Metasome very narrow, composed of 6 well-
defined segments. Eyes well-developed or rudimentary, being placed on distinctly
defined lobes at the outer corners of the frontal margin. Superior antenna? is-
suing far apart, just beneath the ocular lobes, and consisting
of a Sarticulate
peduncle and 2 unequal filiform flagella. Inferior antennse much smaller than
the superior, and sometimes having at the end of the peduncle a small squami-
form appendage. Mandibles rather strong, each with a well-developed molar expansion
and a triarticulate palp. Anterior niaxilke with 2 masticatory lobes, palp biarticulate
and terminating in a number of slender seise ; posterior ones normally developed,
though rather small. Epignath of maxillipeds rather large, forming a broad
vaulted plate, terminating in a digitiform point. The 2 anterior pairs of legs
unlike,
the others, and provided at the base with a small biarticulate exopodite; 1st pair
distinctly cheliform and much Districted at the base, with the ischial joint obsolete;
2nd pair very powerful, fossorial in character, the outer joints being coniplanated
and edged with strong spines. Pleopoda well developed and having the rami
tipped with long natatory seise. Uropoda biramous, ranii filiform, multiarticulate,
the inner one much the longer. Incubatory pouch normal.
Remarks. - This family is well distinguished from that of the Tanaidce
by the gradually tapering, and slightly depressed body, the greater development of the
cephalosome, the peculiar structure of the antennse and of the 2nd pair of legs,
and the presence of a rudimentary exopodite at the base of the 2 anterior pairs