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107
Gen. 2. Astacilla., Fleming.
(Fncycl. Brit. 7th edit. Vol. VII).
Synon. Leachia, Johnston (non Lesueur).
Slægtskarakter. Legemet mere eller mindre
langstrakt. cylindriskt. 4tle Forkropssegment stærkt forlænget,
hos Hannen meget smalt, hos Hunnen bredere og nedad
udvidet til Dannelsen af Brystposen. 2det Par Folere
med Svøben ganske kort, 3-leddet, saugtakket i den indre
Kant og endende med en skarp Torn. lste Fodpar med
alle Led brede og pladeforinige, sidste Led. ovalt og
forsynet med en tydelig Klo. Brystposen kun dannet af 2
valvelformige Plader tilhørende 4de Forkropssegment.
Bemærkninger. Hvad der hovedsageligt skiller denne
Slægt fra foregaaende er Brystposens væsentlig forskjellige
Bygning. I Forbindelse hermed staar ogsaa den
uforholdsmæssige Udvikling af 4de Forkropssegment, der giver de
herhen hørende Former et meget eiendommeligt Udseende.
Den af Johnston foreslaaede Slægtsbenævnelso Leachia kan,
skjøndt den har Prioriteten tor Flemings, ikke bibeholdes,
da dette Navn allerede tidligere er anvendt i Zoologien,
nemlig for en Cephalopodeslægt. Ikke faa Arter af
nærværende Slægt er beskrevne fra forskjellige Have, men de
er ialmindelighed alle blevne henførte under Slægten
Arc-turus.
Gen. 2. .A.S1 acilla. Fleming.
(Encyel. Brit, 7th Edit. Vol. VII).
Si/non. Leachia, Johnston (non Lesueur).
Generic Character. — Body more or less elongate,
cylindrical. Fourth pedigerous segment greatly produced:
in female broader, and, below, dilated — to form the
marsu-pium. Second pair of antennæ, with flagellum quite short,
three-jointed, serrate along the inner edge, and terminating
in a sharp spine. First pair of legs with all the joints
broad and lamelliform. terminal joint oval and furnished
with a distinct claw. Marsupium composed of only 2 valvular
plates, belonging to 4th pedigerous segment.
Remarks. — The character that principally causes this
genus to dift’er from the preceding, is the essentially
deviating structure of the marsupium. In conjunction with
this distinctive divergence, comes the disproportionate
development of the 4th segment, giving to all the forms
belonging to the genus a very peculiar aspect. The generic
appellation Leachia, suggested by Johnston, though with a
prior claim to Fleming’s, cannot be retained, that name
having already been adopted in zoology, viz. to designate
a genus of Cephalopods. Not a few species of the present
genus have been described from specimens taken in various
parts of the ocean; they have well-nigh all. however, been
referred to the genus Arcturus.
23. Astacilla granulata (G. O. Sars).
(Pl. IX. Fig. 27—:«).
Leachia granulata, fx. O. Sars. Prodromus descript. Crust, etc. No. 7:1
(1870).
Astacilla amcricana, Harger, Am. Journ. Sci. III. Vol. XV. pp. :;74
(1878).
Astacilla granulata, Harger, Report on the marine Isopoda of New
England, pg. 364, PI. VIII & IX. Fig. 48—53.
Artskarakteristik. Legemet hos Hunnen omtrent 7
Gange længere end bredt, oventil forsynet med talrige smaa
afrundede Tuberkler. Hovedet oventil med en noget større,
tvedelt Tuberkel. 4de Forkropssegment hos Hunnen
indtagende mere end ’/3 af Totallængden, noget udvidet fortil
og paa sin Overflade granuleret af smaa ensformigt
udviklede Knuder; hos Hannen overordentlig smalt, cylindriskt.
De 3 bagre Forkropssegmenter med triangulært tilspidsede
Epimerer. Bagkroppen forholdsvis kort, med sidste
Segment kun lidet udtrukket i Enden, oventil stærkt knudret
og ved Basis forsynet med 2 triangulære Sidefortsatser.
23. Astacilla granulata (G. O. Sars), n. sp.
Pl. IX. figs. 37—35.
Leachia granulata, G. O. Sars, Prodromus descriptionis Crust, etc.
No. 70 (187(1).
Astacilla amcricana, Harger, Am. Joum. Sci. III, Vol. XV, p. 374
(1878).
Astacilla granulata, Harger, Report on the marine Isopoda of New
England, p. 4(14, PI. VIII it IX, figs, 48—52.
Specific Character. — Body in female about 7 times
longer than broad, furnished above with numerous small
rounded tubercles. Head, above, with a somewhat large
bifurcate tubercle. Fourth segment, in female, measuring
more than one-third of the total length, somewhat dilated
anteriorly, and, on its surface, granulated with small,
uniformly developed protuberances; in male, remarkably
slender, cylindric. The three posterior pedigerous segments
with triangular-pointed epimera. Abdomen comparatively
short, with the terminal segment but slightly produced
toward the extremity; above, exceedingly rugged, and
14»
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