102 
Side rucr Basis af Endosegmentet og lige under den trian- 
guhere Sidefortsats mecl en kort og tyk St ilk og lean ved 
sseregne Muskier slaaes til Siden ligesom de 2 Eloie paa 
en Port. Ved Spidsen baerer de liver 2 korte ovale Ende- 
grene, hvoraf den ene' er sserdeles liden og ganske diekket 
af den an den (se Fig. 21) sam| besat med korte Burster. 
Farven er i levende Tilstand ensfonuig skidden gul- 
brun, 0inenes Pigment kulsort. 
Ltengden af de storste erholdte Individer er. fraregnet 
Folerne, 40”"". 
Forekomst. Flere smukke Exeniplarer af denne char- 
acteristiske Isopode toges under Expeditionens lste Togt i 
Havet 0st af Island (Stat. 48) fra et Dvb af 300 Fame. 
Under sidste Togt erholdtes endnu et Par Exeniplarer af 
sannne Art udenfor Yestkysten af Spitsbergen (Stat. 359), 
Dybden 410 Fame. 
Udbredning. Alien er tidligere kjeiidt fra Fferocrne. 
Island, Spitsbergen. Gronland og Polarflerne, og maa be- 
tragtes som en mgte arktisk Form. 
21. Arcturus tuberosus, G. O. Sars, n. sp. 
(PI. IX. Fig. 22). 
Aretimis tuberosus, Gr. O. Sars, Prodromus descript. Crust, etc-., No. 72 
(1870). 
Arcturus bajfini, var. Feildeni, Mirra, Report on the Crustacea collected 
by the Naturalists of the arctic Expedition in 187,7 — 70 (Ann. 
Nat. Hist. 1877), pg. 14, PI. TTT, Fig. 1. 
Artscharaeteristik. Legemet noget mere under, sietsigt 
end bos foregaaende Art, uden tydelige Haar og mien dorsale 
Torner, men med uregelnuessig knudret Overflade. Epi- 
mererne paa de 3 bagerste Eorkropssegmenter stumpt til- 
spidsede. Endesegmentet med jevnt hvrelvet Overbade, 
Oinene store, triangulsert nyreformige. 2det Par Fdlere 
betydelig lamgere end Legemet, med 7-leddet Svobe. Far- 
ven blegt kjodfarvet. Laengden 35’"’". 
Findested. Stat, 1 8. 
Bemserkninger. Den her omhandlede Form staar 
foregaaende saa ovennaade nasr, at jeg har vseret i stor 
Tvivl om dens Gyldighed som distinct Art, isser da der 
blot forelan til Unders0gelse et enkelt Exemplar. Jeg op- 
fprte den derfor i min Prodromus kun med Forbehold som 
en ny Art og yttrede, at den muligvis kun vilde vise sig 
at vim* en ganske tilfaeldig Yarietet af foregaaende. Aaret 
efter blev iinidlertid den sainme Form beskrevet af Miers 
fra den Engelske Nordpolexpedition i 1875 — 76 og angivet 
at forekomme endog i Msengde paa en Loealitet, uden at 
at the base of the terminal segment, and immediately be- 
neath the triangular lateral projection, by a short and thick 
pedicle, and admit, by the use of specially adapted muscles, 
of being pushed hack, like the leaves of a folding door. 
At the point, they have each 2 short, ovate terminal branches, 
one of which is exceedingly small and completely covered 
by the other (see fig. 21), as also beset with short bristles. 
Colour, when alive, a uniform dirty yellowish-brown; 
ocular pigment a coal-black. 
Length of the largest specimens obtained — excluding 
the antennae — 40""". 
Occurrence. — Several fine examples of this charac- 
teristic Isopod were collected on the 1st cruise of the Ex- 
pedition, in the open sea, east of Iceland (Stat. 48), from 
a depth of 300 fathoms. On the last cruise two more 
specimens of the same animal were taken, off the west 
coast of Spitzbergen (Stat. 359); depth 416 fathoms. 
Distribution. — The species had been previously 
known from the Faeroes, Iceland, Spitzbergen, Greenland, 
as also the Islands of the Polar Sea, north of America, and 
must, therefore, be regarded as a true Arctic form. 
21. Arcturus tuberosus, G. 0. Sars, n. sp. 
(PI. IX. fig. 22). 
Arcturus tuberosus, (7. 0. Sars, Prodromus descriptions Crust etc.. No. 
72 (1876). 
Arcturus baffini, var. Feildeni, Miers, Report on the Crustacea collected 
by the Naturalists of the Arctic Expedition in 1875 — 76 (Ann. 
Nat. Hist. 1877), p. 14, PI. Ill, fig. I. 
Specific Character. — Body a trifle more thickset 
than in the preceding species, without distinctly perceptible 
hairs and without dorsal spines, but presenting an irregular 
rugged surface. Epimera on the 3 posterior pedigerous 
segments obtusely pointed. Terminal segment with uni- 
formly arcuate surface. Eyes large, triangular -reniform. 
Second pair of antennae considerably longer than body, 
with a seven-jointed flagellum. Colour a light pink. Length 
Qfymm 
Locality. — Stat. 18. 
Remarks. — The form to be treated of here approx- 
imates so closely the preceding, that I have felt very greatly 
in doubt concerning its title to specific distinctness, and 
the more so since, but one specimen only lay before me 
for examination. Hence, I recorded the animal in my “Pro- 
dromus” with considerable reservation as a new species, 
stating that it possibly would turn out to be a mere casual 
variety of the preceding. Meanwhile, the year after the 
same form was described by Miers from tlu* English North 
Pole Expedition in 1875 — -76, and said by him to occur 
