—- or ee 
—— 
Par Branchialfodder. 
_kraftige Torner. 
Dens Storrelse tiltager noget 
indtil 4de Par, hvor den er storst, og aftager saa 
igjen successivt paa de bagenfor liggende Par (se 
Tab. Il, Fig. 1). Paa iste Par (Tab. III, Fig. 3) 
er dens ventrale Lap betydelig storre end den dor- 
sale og smalt tillobende i Enden, medens ‘hin er 
jevnt afrundet. Paa de folgende Par (Fig. 4, 5) 
bliver Forskjellen mellem de 2 Lappe efterhvert 
mindre, og paa sidste Par (Fig. 6) er Forholdet det 
omvendte af hvad det er paa lste Par, idet den dor- 
sale Lap her er den storste og mere smalt udlobende 
end den ventrale. Saavel Exopoditen som Epipoditen, 
men iseer denne sidste, viser den for Gjelleelemen- 
terne hos andre Krebsdyr characteristiske spongiose 
Structur, idet der mellem de 2 Lameller, hvoraf 
begge disse Vedheng begrendses, findes et compli- 
ceret System af med hinanden anastomoserende Hul- 
’ rum, hvori der hos det levende Dyr foregaar en 
livlig Blodcirculation. At begge disse Vedheeng der- 
for er af respiratorisk Betydning, er ganske utvivl- 
somt, skjondt, som senere skal vises, ogsaa selve 
Rygskjoldet spiller i denne Henseende en vigtig 
Rolle. 
De 4 forreste Par Bagkropslemmer (se Tab. I, Fig. 
1) er overordentlig kraftigt udviklede Svommeappa- 
rater, der i flere Henseender, og ogsaa i den Maade, 
hvorpaa de beveges, minder om Copepodernes Svom- 
mefedder. De er alle byggede efter samme Type 
og bestaar hvert (se Tab. III, Fig.7 og 9) af en med 
talrige sterke Muskelbundter fyldt, noget affladet 
Basaldel, og to fra dennes Ende udgaaende, med 
cilierede Svommeborster forsynede, enleddede Grene 
eller Aarer, hvoraf den ydre ialmindelighed er ret- 
tet sterkt udad og i Yderkanten bevebnet med 
Paa alle Par findes ved Enden af 
Basaldelen paa den indre Side en eiendommelig 
indadrettet Fortsats (Fig. 8), der moder den tilsva- 
rende paa den anden Side og i Spidsen er beveebnet 
med et Antal, sedvanlig 4, krogformige Torner 
(Fig. 8a). Ved disse Torner hegtes de 2 til samme 
Par herende Fodder ligesom sammen, saa at deres 
Bevegelser kun kan ske samtidigt. 
iste Par Svommefodder (Fig. 7) skiller sig kjen- 
_ deligt fra de ovrige, saavel ved Basaldelens Form 
og Bevebning som ved Beskaffenheden af den ydre 
Gren. Basaldelen, der ligesom paa de ovrige Par 
har et ganske kort Rodled, er her forholdsvis len- 
gere og smalere, noget aftagende i Brede mod En- 
den, og beveebnet med 4 lange Torner, hyoraf en er 
19 
crosses the epipodite from its point of attachment. 
As was the case with the exopodite, there is also 
some difference in the size and form of the epipo- 
dite in the various pairs of branchial feet. The size 
inereases somewhat until the 4th pair, where it is 
greatest, and it then diminishes again, successively, 
in the pairs situated behind (see Pl. II, fig. 1). In 
the 1st pair (Pl. ITI, fig. 3) the ventral lobe is con- 
siderably greater than the dorsal one, and projects 
in a narrow pointed form at the extremity, while 
the latter is evenly rounded. In the succeeding 
pairs (figs. 4,5) the difference between the two lobes 
becomes gradually less, and in the last pair (fig. 6) 
the relation is the reverse of what it was in the 
Ist pair; as the dorsal lobe is here the largest one 
and more narrowly projecting than the ventral one. 
Both the exopodite and the epipodite, but especially 
the last-named, exhibit the characteristic spongy 
structure for the gill-elements in other crustacea; 
as between the 2 lamella by which the appendages 
of both are limited, there is found a complicated 
system of cavities, anastomosing with each other, 
in which, in the living animal, an active blood cir- 
culation proceeds. That both these appendages are 
therefore of respiratory importance is perfectly indu- 
bitable, although, as will be subsequently shown, 
the carapace itself also plays an important part 
in that respect. 
The 4 foremost pairs of the posterior appen- 
dages of the body (see Pl. II, fig. 1) are extremely 
powerfully developed swimming legs which, in 
several respects as well as in the manner in which 
they are moved, remind us of the swimming feet of 
the Copepods. They are all constructed on the same 
type, and consist, each (see Pl. III, figs. 7 and 9), 
of a somewhat flattened basal part filled with nu- 
merous strong bundles of muscles, and two branches 
or oars, issuing from its extremity and furnished with 
ciliated swimming-bristles. Of these branches the 
outer one is usually directed strongly outwards, and 
is armed on the outer edge with powerful spines. 
In all the pairs there is found, at the extremity of 
the basal part on the inner side, a peculiar projec- 
tion directed inwards (fig. 8), which meets the corre- 
sponding one of the other side, and is armed at the 
point with a number — usually 4 — uncinate spines 
(fig. 8a). The 2 feet pertaining to the same pair 
are, as it were, hooked together by these spines, so. 
that their movements can only take place simul- 
taneously. 
The Ist pair of swimming feet (fig. 7) are per- 
ceptibly distinguished from the others, both by the 
form and armature of the basal part as well as by 
the nature of the outer branch. The basal part 
which, as upon the other pairs, has a quite short 
basal joint, is here relatively longer and narrower, 
somewhat narrowing in breadth towards the extre- 
