antaget en pigformig Character, dannende den umid- 
delbare Fortsettelse af Leddet. Den terminale Fort- 
sats af Overleben, ligesom de nu steerkt forleengede 
Halefortsatser viser sig rundtom tet besatte med 
korte Pigge. Paa det bagre Afsnit af Legemet be- 
meerkes de forste Anleg til Rygskjoldet og til de 
6 forreste Par Fodder. Alle disse Dele er dog endnu 
dekkede af Larvehuden, som uden nogensomhelst 
Afbrydelse strekker sig over dem. Rygskjoldet 
(den senere Skal) har Formen af 2 smaa, endnu ikke 
med hinanden dorsalt forbundne afrundede Folde 
helt fortil, i hvis Indre den forste Antydning til 
Skalkjertelen lader sig paavise. Fodderne har endnu 
kun Udseende af en Rekke af 6 ubetydelige knop- 
formige Fremspring langs Siderne af Kroppen umid- 
delbart bag Anlegget til Rygskjoldet. De aftager 
successivt i Storrelse bagtil, og de 2 sidste Par er 
kun meget svagt antydede. I det indre af det ser- 
deles gjennemsigtige Legeme sees nu Tarmkanalen 
med stor Tydelighed. Den har bagtil sondret en 
vel begreendset, sterkt muskulos Endetarm, og gaar 
fortil ud i 2 korte blindsekformige Udvidninger: den 
forste Begyndelse til den senere saa complicerede 
Lever. De forskjellige Muskler, der tjener til 
Aarernes og Mandibularfoddernes Bevegelse kan nu 
med stor Tydelighed adskilles, og Larven beveger 
sig ogsaa i dette Stadium adskilligt mere energiskt 
end i de tidligere. 
I det neste her afbildede Stadium (Fig. 5) har 
Larven en Lengde af 0,87 mm, og viser en videre 
Udvikling af det bagre Afsnit af Legemet, som nu, 
inclusive de terminale Forsatser, er over 3 Gange 
saa langt som det forreste. De Dele, der paa fore- 
gaaende Stadium, viste sig umiddelbart indenfor 
Larvehuden, nemlig Rygskjoldet og de 6 Par Fod- 
knuder, treder nu alle frit frem fra Legemets Over- 
flade og har tiltaget noget iStorrelse. De sammen- 
satte ine er ligeledes betydelig sterre og er ryk- 
kede noget nermere sammen, skjondt de endnu er 
skilte i Midten ved et tydeligt Mellemrum. Ethvert 
af dem er nu omgivet af en klar Bram, hvori senere 
de enkelte Synselementer udvikler sig. I Bygningen 
af de 3 Par oprindelige Nauplius-Lemmer viser ikke 
Larven nogen vesentlige Forskjelligheder fra samme 
hos det sidst beskrevne Stadium. En Foler af Iste 
Par er afbildet meget sterkt forstorret Fig. 5a; 
den viser, som det vil sees, fuldkommen det samme 
rudimentere Udseende som hos de yngste Larver. 
Fig. 6 fremstiller en Larve i et senere Stadium, 
seet fra venstre Side, med den tilsvarende Aare 
udeladt, for at vise de af denne dekkede Dele af 
Hovedet tydeligere. Larvens Lengde er lidt over 
1mm. De 2 Afsnit af Legemet viser sig meget 
104 
| 
distinctly defined, and the bristle projecting from 
the last joint but one has acquired a spiniform 
character, forming the immediate continuation of 
the joint. The terminal protuberance of the labrum, 
as also the now greatly elongated caudal projections, 
appear thickly covered all round with short spines. 
On the posterior section of the body, the earliest 
rudiments of the carapace and of the 6 foremost 
pairs of legs are observable. All these parts, how- 
ever, are still covered by the larval skin, which is 
stretched over them without any interruption what- 
ever. The carapace (the future shell) is in the 
shape of 2 small, rounded folds right in front, and 
not connected dorsally with one another, inside 
which the earliest indication of the shell-gland may 
be made out. The legs have still only the appea- 
rance of a row of 6 small, bud-like projections 
along the sides of the body, immediately behind 
the rudiment of the carapace. They diminish in 
size successively behind, and the last 2 pairs are 
only very faintly indicated. In the interior of the 
exceedingly transparent body, the intestinal canal 
is now seen with great distinctness. Posteriorly, 
a well-defined, very muscular rectum has been di- 
vided off, and in front, it forms 2 short ceecal expan- 
sions, — the earliest commencement of the subse- 
quently so complicated liver. The different muscles 
employed in the motion of the oars and the mandi- 
bular legs, can now be very clearly distinguished, 
and the larva moves much more energetically in 
this stage than in the earlier ones. 
In the next stage represented here (fig. 5) the 
larva has a length of 0.87 mm. and exhibits a 
further development of the posterior section of the 
body, which now, including the terminal projections, 
is more than 3 times as long as the anterior sec- 
tion. Those parts which in the preceding stage 
appeared immediately within the larval skin, viz. 
the carapace and the 6 pairs of pedal buds, now 
all project freely from the surface of the body, and 
have somewhat increased in size. The compound 
eyes are also considerably larger, and have moved 
a little nearer together, though they are still sepa- 
rated in the middle by a distinct space. They are 
both surrounded by a clear rim, in which the visual 
elements are subsequently developed. In the struc- 
ture of the 3 pairs of original nauplius limbs the 
larva presents no essential difference from those in 
the last-described stage. One antenna of the Ist 
pair is shown, very highly magnified, in fig. 5 a; 
as will be seen, it presents exactly the same rudi- 
mentary appearance as in the youngest larva. 
Fig. 6 represents a larva in a later stage, seen 
from the left side, with the left oar omitted in order 
to show more distinctly those parts of the head 
which it covers. The length of the larva is a little 
over 1 mm. The 2 sections of the body appear 
r 
