120 
Hovedet (se Tab. XIX, Fig. 1 og 11) er af 
enorm Storrelse, og viser, seet fra Siden, en neesten 
halvymaanedannet Form. Det fortsetter sig nedad 
umiddelbart i et serdeles stort, leformigt krummet 
Rostrum, der er rettet skraat nedad og bagud. Dets 
dorsale Kant er kjolformigt tilskjerpet og danner 
en fuldkommen jevn og uafbrudt Bue lige til Spid- 
sen af Rostrum. ‘Til hverSide sees en anden meget 
tydelig og noget uregelmessig bugtet Kjol, hvorved 
Hovedets Sideflader deles i en dorsal og en ventral 
Area. Denne Kjol, der aabenbart svarer til den 
saakaldte Fornix hos Cladocererne og navnlig viser 
en umiskjendelig Lighed med samme hos Lynceiderne, 
begynder ved Kindbakkernes Feste og strekker sig 
herfra med en ganske svag Krumning skraat fortil, 
henimod Midten af Hovedets Lengde, hvorpaa den 
gjor en meget sterk, nesten vinkelformig Boining 
og lober skraat bagtil langs Siderne af Rostrum, 
endende med et kort tandformigt Fremspring i 
nogen Afstand fra Spidsen. Sees Hovedet lige for- 
fra (Tab. XVIII, Fig. 4), viser denne laterale Kjol 
sig sterkt fremspringende i sin proximale Del, idet 
den her som et Hvelv dekker over Basis af Aarerne. 
Lengere nedad nermer de 2 Kjole sig til hinanden 
og gjor derved Indtrykket af en tydelig Indknibning 
at Hovedet ved Basis af Rostrum. Dette sidste 
viser sig i denne Stilling af Hovedet ligesom tredelt 
i Enden, gaaende i Midten ud i en sterk dolk- 
formigt tilspidset Fortsats, og til hver Side af 
denne i et betydelig kortere tandformigt Fremspring, 
der danner Enden af de laterale Kjole. 
Nakkesegmentet (se Tab. XIX, Fig. 1 og 11) 
er ganske kort og begrendset fra Hovedet ved en 
vel markeret Tversutur, ved hvis Ender Kindbak- 
kernes ovre Del er festet. Det er ganske svagt 
hvelvet oventil og viser til hver Side en kort, 
skraat opadgaaende Ribbe, der paa en Maade er en 
Fortseettelse af Hovedets laterale Kjole. 
Truncus er omtrent af Hovedets Lengde og 
temmelig tyk fortil, men afsmalnes hurtigt og 
jevnt bagtil. Den er delt i 12 uniforme Segmenter, 
hvert berende et Par Branchialfodder. Dorsalsiden 
af Segmenterne er ganske glat, uden Borster. Der- 
imod udgaar fra Siderne af de 2 bagerste Segmenter 
et Par eiendommelige, lateralt udbredte Plader, hvor- 
til intet tilsvarende findes hos andre Phyllopoder. 
Disse Plader (Fig. 9, 1), som alene forefindes hos 
Hunnen, er af ikke ubetydelig Storrelse, bladformige, 
og gaar ud i 3 triangulert tilspidsede Flige, hvoraf 
den forreste er storst. Ifolge sin Stilling synes de 
nermest at vere bestemte til at stotte de 2 kage- 
formige AZgmasser, som beeres under Skallen. 
The head (see Pl. XIX, figs. 1 and 11) is of 
enormous size, and when seen from the side, ex- 
hibits an almost semi-lunar shape. It is continued 
downwards into an exceedingly large, falciformly 
curved rostrum, which points obliquely downwards 
and backwards. Its dorsal margin is sharpened in 
the form of a keel, and forms a perfectly even 
and uninterrupted curve right to the point of the 
rostrum. On each side is visible another very dis- 
tinct, and somewhat irregularly wavy keel, by which 
the lateral surfaces of the head are divided into a 
dorsal and a ventral area. This keel, which evi- 
dently answers to the so-called fornix in Cladocera, 
and notably exhibits an unmistakable resemblance 
to that in the Lynceide, commences at the place of 
attachment of the mandibles, and runs thence with 
a very gentle curve obliquely forwards to about 
the middle of the length of the head, where it 
makes a very sharp, almost angular bend, and runs 
backwards along the sides of the rostrum, ending 
in a short, dentate projection at some distance from 
the point. When the head is seen from the front 
(Pl. XVIII, fig. 4), this lateral keel appears very 
prominent in its proximal part, where it covers the 
base of the oars like an arch. Farther down, the 
2 keels approach one another, thereby giving the 
impression of a distinct contraction of the head at 
the base of the rostrum. The latter appears, in 
this position of the head, as if tripartite at the 
extremity, being produced in the middle to a strong, 
mucronate projection, on each side of which is a 
considerably shorter, dentiform prominence, forming 
the end of the lateral keel. 
The cervical segment (see Pl. XTX, figs. 1 and 
11) is quite short and separated from the head by 
a well-marked transverse suture, to the ends of 
which the upper portion of the mandibles is attached. 
It is very slightly arched above, and shows, on 
each side, a short, obliquely-ascending bar, which 
in one way is a continuation of the lateral keel of 
the head. 
The trunk is of about the same length as 
the head, and rather thick in front, but tapering 
rapidly and evenly behind. It is divided into 12 
uniform segments, each carrying a pair of branchial 
legs. The dorsal surface of the segments is quite 
smooth, and without bristles. On the other hand, 
from the sides of the two hindmost segments, there 
issues a pair of peculiar, laterally-extended lamine, 
to which there is nothing corresponding to be found 
in other Phyllopoda. These lamine (fig. 9,1) which 
are only found in the female, are of no inconside- 
rable size, are foliate and project into 3 triangularly- 
pointed lobes, of which the foremost is the largest. 
Judging from their position, they appear to be 
intended to support the 2 cake-like masses of eggs 
that are carried beneath the shell. 
