lig udpreget Sondring af Midtkrop og Bagkrop fin- 
des ikke. Men, i Lighed med hvad vi har gjort med 
Lepidurus, lader sig maaske Greendsen mellem begge 
sette ved det 1lte Segment, der berer det bagerste 
af de 3 Par Branchialfodder, hvis Exopoditer er om- 
formede til Feste for Agmassen, og hvor ogsaa 
Kjonsaabningerne har sin Plads. 
Haledelen (se Tab. XVI, Fig. 7) er ganske kort, 
usegmenteret, og omboiet mod Bugsiden. Den er i 
sin forreste Del temmelig tyk, men udvides bagtil 
mod Enden til 2 tynde, jevnsidesliggende Plader, 
der hver nedad springer frem i Form af en tornformig 
Fortsats. Ovenfor denne Fortsats er Randen af 
hver Plade delt i et noget vekslende Antal (fra 8 
til 15) smaa tandformige Fremspring cilierede i Kan- 
terne. Hvor Pladerne ophorer oventil, er der i Mid- 
ten en liden Knude, hvorpaa er festet 2 fint cili- 
erede 2-leddede Borster (Haleborsterne), og ovenfor 
dem igjen er den sterkt convexe, neesten helformigt 
fremspringende Rygflade af Halen bevebnet med 
omkring 6 sterke bagudboiede Torne, fint tandede 
i Kanterne, og ordnede i 2 uregelmessige Rader (se 
ogsaa Fig. 7, bis). Til den afstumpede Ende af 
Haledelen er bevegeligt indleddede 2 serdeles lange 
og sterke, men kun ganske svagt boiede Klor (Hale- 
klorne), der morphologiskt synes at svare til Hale- 
traadene hos Apodiderne og den saakaldte Furca hos 
Branchipodider og Phyllocarider. De afsmalnes grad- 
vis mcd Enden, som gaar ud i en fin Spids, og har 
langs den bagre, noget concave Side talrige smaa 
Tagger samt desuden i sin basale Del et Antal af 
fine Borster. 
De sammensatte Mine (se Tab. XV, Fig. 2, 3, 4, 0) 
har, som ovenfor nevnt, sin Plads i det indre af den 
koniskt fremspringende Pandedel, hvis stumpt til- 
rundede Ende de nesten fuldsteendigt udfylder. De 
ligger meget ner sammen og stoder endog hos fuld- 
voxne Individer umiddelbart til hinanden i Midt- 
linien (se Fig. 3, 4). Seet fra Siden (Fig. 2) har 
hvert Gie en fuldsteendig cirkelrund Form, hvorimod 
de, ovenfra eller nedenfra seet, viser sig paatveers 
ovale. Begge Mine er (se Tab. XVI, Fig. 10, 0) om- 
givne af en felles tynd og gjennemsigtig Membran 
og bestaar af et meget betydeligt Antal af Syns- 
elementer, hvis ydre Del, som sedvanlig, har For- 
men af sterkt lysbrydende korte Kegler indplantede 
med sin Spids i det morke Giepigment. Dette sidste 
har en noget lysere overfladisk Skikt, hvorfor Kry- 
stalkeglerne indenfor Kanterne af Oiet tager sig ved 
paafaldende Lys ud som tet sammen liggende regel- 
meessige morke Pletter, medens de i Peripherien 
danner en klar Brem, eller Indfatning om Wiet. 
Minene er til en vis Grad bevegelige, idet de dels 
kan trekkes noget tilbage i Hovedet, dels noget 
90 
ments being the most highly developed. There is no 
distinctly-marked division of the mesosome and me- 
tasome; but as in Lepidurus, we may perhaps place 
the boundary between the two, at the 11th seg- 
ment, which carries the hindmost of the 3 pairs of 
branchial legs whose exopodites are transformed to 
support the egg-mass, and where, too, the genital 
openings are situated. 
The caudal part (see Pl. XVI, fig. 7) is quite 
short, unsegmented and curved towards the ventral 
surface. In its anterior part it is rather thick, but 
expands posteriorly towards the extremity into 2 thin, 
juxtaposed lamella, each of which projects below in 
the form of a spiniform prominence. Above this 
prominence, the margin is divided into a somewhat 
varying number (from 8 to 15) of small dentiform 
projections with ciliated margins. Where the lamelle 
end above, there is, in the middle, a little tubercle, 
to which are attached 2 finely-ciliated, 2-jointed 
bristles (caudal bristles), and above them again is 
the highly convex, almost heel-like, projecting dorsal 
surface of the tail, armed with about 6 strong, 
backward-curved spines, finely dentated at the edges, 
and arranged in 2 irregular rows (see also fig. 7, bis). 
To the blunt end of the caudal part, 2 particularly 
long and strong, but only very slightly curved 
claws (caudal claws) are movably articulated; they 
seem, morphologically, to correspond to the caudal 
filaments in the Apodide, and the so-called furea in 
the Branchipodide and Phyllocaride. They taper 
gradually towards the extremity, which is very 
finely pointed, and along their posterior, somewhat 
concave side they are clothed with numerous small 
teeth, and moreover in their basal part with a 
number of fine bristles. 
The compound eyes (see Pl. XV, figs. 2, 3, 4, 0) 
are situated, as already mentioned, inside the coni- 
cally projecting frontal part, almost filling its bluntly 
rounded end. They le very close together, and 
even touch one another in the median line in full- 
grown animals (see figs. 3, 4). Seen from the side 
(fig. 2), each eye has a perfectly circular shape, 
whereas seen from above or below, they appear 
transversely oval. Both eyes (se Pl. XVI, fig. 10, 0) 
are surrounded by a thin and transparent common 
membrane, and consist of a very considerable num- 
ber of visual elements, whose outer part has, as 
usual, the shape of short, highly-refractive cones, 
with their point planted in the dark ocular pigment. 
This pigment has a rather lighter superficial coating 
causing the crystalline cones within the margin of 
the eye to appear, when the light falls upon them, 
like closely-adjacent, regular, dark spots, while those 
in the periphery form a clear rim or setting round 
the eye. The eyes are movable to a certain extent, 
being partly capable of slight retraction into the 
head, partly of being slightly turned on their axis. 
