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42
Ved Basis af dette ligesom de 3 følgende Fodpar er
fæstet 2 vel udviklede Gjeller, og foran dem danner
Bodleddet et knudeformigt. med et Bundt af lange, bugtede
Børster besat Fremspring.
2det Fodpar (Fig. 19) er af samme Størrelse og
Bygning som 1ste Par og skiller sig kun ved et noget af.-igende
Længdeforhold mellem 3die og 4de Led samt derved, at
Saxenes Fingre er noget længere.
3die Fodpar (Fig. 20) er af meget spinkel Bygning
og stærkt forlænget, omtrent af hele Forkroppens Længde.
3die Led er lidt kortere end 4de og begge langs sin indre
Kant bevæbnede med en enkelt Bad af spidse Torner
foruden fine Børster. Sidste Led er stærkt forlænget og tyndt,
noget afsmalnende mod Enden og forsynet med spredte
Børsteknipper. Endekloen er omtrent halvt saa lang,
lefor-mig sammentrykt og langs sin indre Kant besat med line
Torner. Svømmegrenen er fuldkommen af samme Udseende
som paa de 2 foregaaende Par, og heller ikke det
knude-formige børstebærende Fremspring ved Basis mangler.
4de Fodpar skiller sig i ingen Henseende fra
foregaaende Par.
Derimod viser sidste Fodpar (Fig. 21) tydeligt
udprægede Afvigelser. Det er omtrent af samme Længde
som de 2 foregaaende Par, men mindre stærkt afsmalnende
mod Enden og viser et noget forskjelligt Længdeforhold af
de enkelte Led. 3die Led er saaledes her adskilligt længere
end 4de, og mangler ganske Torner, hvorimod Børsterne i
den indre Kant er længere og talrigere. Ogsaa 5te Led
er forholdsvis større end paa de foregaaende Par og neppe
kortere end 4de. Endelig er sidste Led af fuldkommen
lineær Fonn, overalt af ens Brede og i begge Kanter, men
navnlig i den indre tæt besat med korte, kostformige
Borsteknipper. Endekloen er ganske rudimentær, afstumpet i
Spidsen og oftest ganske skjult mellem de fra foregaaende
Led udgaaende Børster.
Gjellerne (se Fig. 22) viser den sædvanlige pyramidale
Fonn og bladede Bygning, men udmærker sig ved sit
betydelige Antal. Man tæller paa hver Side 10 saadanne,
medregnet den ovenfor omtalte supplementære Gjelle paa
sidste Par Kjævefødder. Naar undtages denne sidste og
den allerbageste (se Fig. 21), som begge er uparrede,
eide øvrige ordnede i en dobbelt Bække, saaledes, at til hver
Fod svarer 2 Gjeller (se Fig. 17 og 19).
Bagkroppens Svømmevedhæng (Fig. 23 og 24) er
kraftigt udviklede og bestaar af en tykkere, muskuløs og
noget fladtrykt Basaldel og 2 med talrige cilierede
Bandbørster besatte, smalt lancetformige Grene eller Endeplader.
Af disse sidste er den indre noget kortere end den ydre
og ved Boden i den indre Kant forsynet med et forholdsvist
temmelig stort cylindriskt eller noget kølleformigt Appendix
(se Fig. 24). 1ste Par skiller sig dog i denne Henseende
At the base of this pair of legs, as also of the three
succeeding pairs, are attached 2 well-developed branchiæ.
and, anterior to the latter, the basal joint forms a
tuberculi-fonn projection, furnished with a bunch of long, curving
bristles.
The 2nd pair of legs (fig. 19) are similar in size
and structure to the 1st, being distinguished from them
merely by a somewhat different proportion in length between
the 3rd and 4th joints, as also by the lingers of the chela
being a trifle longer.
The 3rd pair of legs (fig. 20) are very feeble in
structure, and greatly produced, their length about equalling that
of the whole anterior division of the body. The 3rd joint is
a trifle shorter than the 4th. and both exhibit along the
inner margin a single series of sharp-pointed spines,
exclusive of slender bristles. The last joint is greatly
produced. and slender, tapering a little toward the extremity,
and provided with scattered fascicles of bristles. The
terminal claw is about half as long, falciform, and beset
along the inner margin with delicate spines. The natatory
branch has precisely the same appearance as that on the
two preceding pairs, and not even is the bristle-beset,
tuberculiform projection at the base wanting.
The 4th pair of legs are in no respect distinguished
from the preceding pairs.
On the other hand, the last pair of legs (fig. 21)
exhibit distinct deviations. They are about of the same length
as the two preceding pairs, but taper less abruptly toward
the end. as also the proportion in length between the
different joints is somewhat different. Thus, the 3rd joint
is considerably longer than the 4th, and entirely without
spines, whereas the bristles on the inner margin are longer
and more numerous. The 5th joint, too. is comparatively
larger than in the preceding pair, and very little, if at all.
shorter than the 4th. Finally, the last joint is perfectly
linear in form, everywhere of the same breadth, and along
both margins, hut especially the inner, beset with short,
scopitorm fascicles of bristles. The terminal claw is quite
rudimentary, obtuse at the end, and. as a general rule,
entirely concealed among the bristles of the preceding
joints.
The branchiæ (see fig. 22) exhibit the usual
pyramid-ical form and lamellar structure, but are characterized by
their considerable number. On either side occur 10,
including the supplementary branchia mentioned above as
found on the last pair of maxillipeds. If we except this
and the hindmost branchia (see fig. 21), both of which are
odd ones, the rest occur in a double series, so that each
leg has 2 branchiæ (see figs. 17 and 19).
The natatory appendages of the abdomen (figs 2.3. 24)
are powerfully developed, and consist of a thickish, muscular,
and somewhat flattened basal part, along with 2 slender,
lanceolate branches, or terminal plates, beset with numerous
ciliated marginal bristles. 01’ these branches, the inner is
somewhat shorter than the outer, and at the base furnished on the
inner margin with a comparatively large, cylindric, or
somewhat claviform, appendix (see fig. 24). The 1st pair are
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