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Inferior antenna? attaining the length of the body, not including the terminal seg-
ment of metasome, flagellum scarcely
joint, and having the 1st articulation twice as long
more than 1
/s as long as the last peduncular
as the other 2 combined.
Male much smaller than female, and extremely slender, with the middle segment
of mesosome narrow cylindric in form, and quite smooth. Superior
antenna? with
the flagellum much larger than in female, and provided with a greater number of
olfactory filaments. Colour yellowish, clouded with irregular dark brown shadows.
Length of adult female reaching 20 mm., that of male scarcely
that size.
more than half
Remarks. The present species was first described by Sowerby in the above
quoted paper under the name of Oniscus longicornis.
It is, however, very probable
that the form observed by the Eev. Charles Cordiner several years previously,
and named Astacilla, without any specific denomination, was the very same species.
The form recorded by Johnston as Lcacia lacertosa, is undoubtedly this species.
By most of the earlier authors, it has been referred to the genus
Latreille. The Arc-turns yracilis of Goodsir is, in my opinion, nothing
Arcturus of
else than
the adult male of the present species. From the other Norwegian species, it may
be chiefly distinguished by its slender and elongated body, and by the rather
slight development
of the dorsal tubercles.
Occurrence. This species would seem to occur along the whole coast of
Norway, from the Christiania Fjord to Vadso. It is generally
found in moderate
depths, ranging from 10 to 30 fathoms, clinging to Hydroida and Polyzoa, several
specimens, females, males and young, being often associated in the same colony.
By the aid of its 3 posterior pairs of legs, the animal is capable of getting a
rather firm hold on the object to which it is clinging, moving the fore part of its
body freely to and fro in search of food, which is first seized by the long pediform
inferior antenna?. At times it is seen to leave go its hold, and to start off rather
rapidly through the water, in order to affix itself on some other place. This motion
is effected by the aid of the 2 anterior pairs of pleopoda, which in such cases
are protruded from the shelter of the valvular uropoda, and push the animal
forwards. Not infrequently female specimens are found carrying their young brood
affixed all round the long inferior antenna1 , which thereby acquire a peculiar
velvety appearance.
Distribution. British Isles (Sp. Bate). Kattegat (Meinert), Iceland.
12 Crustacea.