12 
som her danner den umiddelbare Kropsveg. Det | dorsal portion, which is of considerably greater 
felgende Afsnit, der forestiller hvad man ialminde- 
lighed pleier at kalde «Truncus> eller «Thorax», men 
som maaske mere passende bor kaldes Midtkroppen 
(mesosome), bestaar af 8, i sin hele Omkreds tyde- 
ligt sondrede, og ensformigt udviklede Segmenter, 
der hvert berer et Par Branchialfodder. Omvendt 
hvad Tilfeldet er med Hovedet, har. dette Afsnit 
sin sterste Udstrekning ventralt, idet begge Afsnit 
forbinder sig med hinanden langs en meget skraat 
gaaende Linie. Maalt langs Dorsalsiden er det her 
omhandlede Afsnit derfor neppe lengere end Hove- 
det, medens det ventralt er nesten dobbelt- saa 
langt. Bagtil forbinder det sig med Bagkroppen, 
uden at vere afsat fra samme ved nogen merkbar 
Indknibning. Det forreste Afsnit af Bagkroppen 
(«<Preabdomen», metasome) er sammensat af 4 Seg- 
menter, alle betydelig storre end de til Truncus 
horende Segmenter, og hvert forsynet med et Par 
kraftigt udviklede Svemmefodder. Det sidste af 
disse Segmenter har tydelige pladeformige Epimerer, 
der ender bagtil med et retvinklet Hjorne. Hele 
Bagkanten af dette Segment er desuden regelmes- , 
sigt sagtakket, og ogsaa paa det foregaaende Seg- 
ment bemerkes i den dorsale Del en lignende, skjondt 
mindre udpreget Bevebning af Bagkanten. Afsnit- 
tet, der successivt afsmalnes bagtil, dekkes til Si- 
derne nesten fuldstendigt af Rygskjoldet, medens 
dets dorsale Del treeder mere eller mindre frit frem 
indenfor den dybe Indbugtning i Rygskjoldets bagre 
Del (se Tab. I, Fig. 2). Angaaende Lengden af 
dette Afsnit, saa er den noget forskjellig hos de 
2 Kjon. Hos Hunnen er det, ialfald maalt langs 
Ventralsiden, neppe lengere end Truncus, medens 
det selv hos endnu ikke fuldt udviklede Hanner (se - 
Tab. Il, Fig. 1) altid er betydelig storre, i Overens- 
stemmelse med den kraftigere Udvikling af Svomme- 
fodderne. Det ydre, meget bevegelige Afsnit af 
Bagkroppen (<Postabdomen», urosome), der gaar i 
Flugt med det forreste') og jevnt og hurtigt af- 
smalnes bagtil (se Tab. I, Fig. 1 og 2), bestaar lige- 
ledes af 4 Segmenter, hvoraf de 2 forreste er for- 
synede med rudimentere Buglemmer, medens de 2 
bagerste ganske mangler saadanne. Det er af trind 
Form, nesten dobbelt saa langt som det forreste 
Afsnit og har Bagkanten af de 3 forreste Segmenter 
regelmessigt sagtakket, ligesom paa de bagre Seg- 
menter af hint. Til Enden af sidste Segment er 
Halegrenene indleddede; de synes at svare til den 
saakaldte Furca hos Copepoderne og tor saaledes 
nermest vere at betragte som et i 2 Dele klovet 
Endesegment. Under Basis af Halegrenene gaar 
sidste Segment ud i 2, ved et smalt mediant Indsnit 
1) Hos Sl. Paranebalia er dette Afsnit skarpt afsat fra Pree- 
abdomen. 
extent than the ventral one, is firmly connected 
to the carapace, which here forms the immediate 
wall of the body. The succeeding section, which 
represents what is usually termed the «truncus» or 
«thorax», but which might perhaps be more properly 
termed the middle section of the body (mesosome) 
consists of 8 uniformly developed’ segments, di- 
stinctly separated throughout their entire circum- 
ference, each of which carries a pair of branchial 
legs. This section, contrary to what is the case 
with the head, has its greatest extent ventrally, 
as both sections are connected to each other along 
a very oblique line of union. Measured along the 
dorsal side, the section referred to here is, therefore 
scarcely any longer than the head, while the ven- 
tral part is almost twice as long. Posteriorly it 
connects to the posterior division of the body 
without being demarcated from it by any notewor- 
thy constriction. The front section of the posterior 
division of the body («preabdomen», metasome) is 
composed of 4 segments, all considerably larger 
than the segments pertaining to the truncus, and 
each furnished with a pair of powerfully developed 
swimming legs. The last of those segments has di- 
stinct lamelliform epimere that. terminate behind 
in a right-angled corner. The entire posterior mar- 
gin of this segment is, further, regularly serrated, - 
and also in the preceding segment there is observed, 
on the dorsal part, a similar although not so distinct 
armature of the posterior margin. The section, which 
diminishes gradually backwards, is almost comple- 
tely covered at the sides by the carapace, while the 
dorsal part appears more or less uncovered inside 
the deep sinus in the posterior part of the carapace 
(see Pl. I fig. 2). Regarding the length of this sec- 
tion, it is somewhat different in the 2 sexes. In 
the female it is, at any rate when measured along 
the ventral side, scarcely longer than the truncus, 
while it, in even not yet fully developed males (see 
Pl. II fig. 1), is always considerably larger, in corre- 
spondence with the more powerful development of 
the swimming legs. The outer, very mobile section 
of the posterior division of the body («postabdomen>, 
urosome) which forms the immediate continuation of 
the anterior one’) and diminishes evenly and ra- 
pidly backwards (see Pl. I figs. 1 and 2) consists 
also of 2 segments, of which the 2 foremost ones 
are furnished with rudimentary ventral appendages, 
while the 2 hindmost ones are quite devoid of such 
appendages. It is cylindrical in form, almost twice 
as long as the foremost section, and has the po- 
sterior edge of the 3 foremost segments regularly 
1) In the gen. Paranebalia this section is sharply defined 
from the preeabdomen. 
