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As our knowledge of this peculiar group of Isopoda is of comparatively recent
date, it is highly probable, that the number of genera will, in course of time, be
considerably increased, and that it will even be found necessary to subdivide
this group into several distinct families.
Gen. 1. MunnOpSlS, M. Sars, 1860.
Generic Characters. Body less compact than in the other genera, with
the anterior division much broader than the posterior. Cephalon of moderate
size, deeply emarginated on each side for the insertion of the antennas, frontal
part narrowly produced. The 4 anterior segments of mesosome transversely ex-
cavated dorsally, with the lateral parts obtuse; the 3 posterior segments densely
crowded together, and very convex above. Caudal segment comparatively large,
oblong oval. Superior antennas with the basal joint very large and massive, flagellum
multiarticulate and much longer in male than in female. Inferior antennas with
the 2 outer joints of the peduncle greatly elongated. Mandibles without any
molar expansion, cutting edge but slightly dentated, palp well developed, with the
terminal joint lamellar, incurved. Maxillipeds pronouncedly laminar,
with the
antepenultimate joint of the palp acutely produced inside, the 2 outer joints
narrow and simple. The first 2 pairs of legs of essentially the same structure, though
somewhat different in size; the 2 succeeding pairs extremely slender and elong-
ated, with the first 3 joints short and thick. Natatory legs of uniform structure,
and rather slender, with the carpal and propodal joints foliaceous and densely
edged with plumose setas, dactylus wanting. Female operculum navicular, male
operculum transformed in the usual manner, digitiform process of the copulative
appendages terminating in a long and slender seta. Uropoda simple, filiform,
Inarticulate.
Remarks. This genus was established in the year 1860 by my late father,
to include a very remarkable Isopod, found by him at Christiansund,
west coast of
Norway. The generic name refers to a certain resemblance, in outward appear-
ance, to the genus Munna of Kroyer. It forms the type of the family Munnop-
xiilic, being the first genus recorded, and it is distinguished pretty well from the
other genera, both by its outward appearance, and by the structure of the several
appendages. In addition to the type species, 4 other species have in recent times
been adduced to this genus. Three of these were procured during the Challenger