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80
E. Miers 1
), the genus comprises, in my opinion, forms which can hardly be placed
in one and the same genus. As to the Norwegian Idothere, they have generally
been considered by recent authors as only varieties of one and the same species.
A close]- examination of i'he large material at my disposal has. however, shown
them in reality to be referable to no less than 6 different species, all easily re-
cognizable
i
in both sexes.
1. Idothea baltiea (Pallas).
(PI. XXXII.)
Oitiscns bfiltirus, Pallas, Spir. Zool. Vol. IX. p. 6fi. PL IV, tig. 6.
Syn: Stenosoma irrorata, Say.
Jilntlica tricnspvlata, I)esm.
tritlenlata, Rathki'.
irrorata, Harger.
marina, Miers.
Specific Characters. Body oblong oval, about 3 times as long
as it is
broad, with the dorsal face perfectly smooth. Coxal plates rather large, occupying
the whole length of the side-edges of the segments, so as to form a broad, conti-
nuous marginal area. Metasome about the length of the 5 posterior segments
combined, terminal segment slightly tapering distally, side-edges straight, tip dis-
tinctly tridentate, middle tooth conically produced, lateral ones much shorter,
though well denned, and each separated from the median tooth by
a well-marked
sinus. Eyes of moderate size, rounded. Superior antenna? with the 1st joint of
the peduncle rather broad, irregularly angular, last joint much longer than the
middle one, flagellum about the length of the former. Inferior antennae rather
elongated, reaching, when reflexed, almost to the end of the 3rd segment of meso-
some, flagellum very slender, being much longer than the peduncle, and composed
of from 16 to 20 articulations. Legs moderately strong, being, as usual, more
powerfully developed in male than in female. Stylet of the 2nd pair of pleopoda
in male not extending to the end of the inner plate. Uropoda with the terminal
plate obtusely truncated at the tip. Colour extremely variable, sometimes uni-
formly yellowish or greenish with small dark dots, sometimes variegated, with
dark brown pigment forming regular longitudinal bands or larger patches arranged
in a perfectly symmetrical manner. Length of adult male reaching to 35 mm.
Remarks. Mr. E. Miers names this form Llotliea marina, believing that
Linnaeus' Oniwns mar'nitt* refers to this species. This is. however, very doubtful,
and as that specific name has been more properly applied to another Tsopod,
') Revision of the Uluteid^. Linn. Sue. Journal. Zoology. Vol. XVI.