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dactylus styliform. Female operculum rounded, without any longitudinal keel;
male operculum transformed in the usual manner. Uropoda not very large, simple,
Inarticulate, distal joint much larger than the proximal one.
Remarks. This genus was established by the present author as early as
in the year 1863, and was at that time included within the group "Isopoda remi-
gantia", answering to the now generally accepted family Munnopsidce. The reason
for this was that the 3 posterior pairs of legs were proved to act as pulling
implements, by which the animal is enabled to move freely through
the water in
a backward direction. In their structure, however, these legs differ rather pro-
minently from those in the true Munnopsidce,
and in most other characters this
genus resembles much more closely the 3 preceding genera, and may therefore
more properly be associated with them in a separate family. In the restriction
here adopted, the genus comprises as yet only 3 species, 2 of which will be de-
scribed below, the 3rd having recently been recorded by
the Bay of Biscay under the name of IJ. elongatum.
1. Desmosoma lineare,
(PI. LIII, PL LIV, fig. 1.)
G. 0. Sars.
M. Jules Bonnier from
Desmosoma lineare, G. 0. Sars, Om en anomal Gruppe af Isopoder. Chv. Vid. Selsk. Forhandl.
1863, p. 11.
Specific Characters. Pody slender, linear in form, being in female almost
5 times as long as it is broad, in male somewhat shorter. Cephalon of moderate
size, irregularly rounded, frontal part somewhat produced, and transversely trun-
cated in female, slightly insinuated in male. The 4 anterior segments of mesosome
differing but little in shape, lateral parts in all of them curving anteriorly, and
terminating in an acute corner, which in male is produced to a strong spiniform
projection. Posterior section of mesosome exceeding in length the preceding part
of the body, and fully as broad, in male even somewhat broader, 1st segment
large and expanded, with the antero-lateral corners acutely produced. Caudal
segment in female semi-oval, in male broader, almost semicircular, edges evenly
curved. Superior antenna? 6-articulate, 2nd joint the longest. Inferior antenna?
in female scarcely longer than the anterior division of the body, last joint of the
peduncle longer than the penultimate one, flagellum about the length
of those
joints combined, and composed of 12 14 articulations. Inferior antenna? in male
considerably larger, attaining half the length of the body, 2nd joint of the pe-
duncle armed outside with a strong spine, the 2 outer joints considerably tume-
fied, and each having 2 spines at the end outside, flagellum pronouncedly fusi-