Paa Grendsen mellem Hovedet og Nakkesegmentet 
ligger de 2 kraftige Kindbakker og tet bag dem 
paa Bugsiden de 2 Par Kjever. Truncus berer 
22—24 Par Branchialfodder og er delt i et tilsva- 
rende Antal meget uniforme Segmenter. Haledelen 
er uden egentlige Lemmer, men berer paa Spidsen 
2 sterke, beveegelige Klor og dorsalt 2 smaa jevn- 
sidesstillede Borster. 
Jeg gaar nu over til at beskrive ethvert af 
disse Afsnit noget ngiere. 
Hovedet (se Tab. XV, Fig. 2, 3, 4) er forholds- 
vis af ringe Storrelse og, seet fra Siden (Fig. 2), af 
uregelmessig triangular Form. Dets dorsale Flade 
er jevnt convex og beerer i Midten et eiendommeligt 
stilket, noget kolleformigt Appendix (af), som ial- 
mindelighed er tydet som et Fastheftningsredskab. 
Pandedelen er steerkt fremspringende, nesten koniskt 
udtrukket, og ender i en stump Spids, indenfor hvil- 
ken de sammensatte Gine har sin Plads. Nedenfor 
Pandedelen har Hovedet en dyb vinkelformig Ind- 
bugtning, hvorved Pandedelen meget skarpt sondres 
fra det triangulert fremspringende Rostrum. Dette 
sidste er noget trekantet i Gjennemsnit, idet det 
oventil har en tilskjerpet Kant, medens det nedentil 
er svagt indhulet langs ad Midten. Bunden af Ind- 
hulingen viser sig, naar Hovedet sees fra Siden, som 
en buet Linie, der strekker sig fra Spidsen af Ro- 
strum bagover mod Basis af Overleben. Seet oven- 
fra (Fig. 3) eller nedenfra (Fig. 4), viser Hovedet 
sig temmelig bredt bagtil, men afsmalnes hurtigt 
fortil mod den smalt tilrundede Pandedel. 
Nakkesegmentet er oventil sondret fra Hovedet 
ved en meget distinct og temmelig dyb Indbugtning, 
i hvis Bund der lader sig paavise en tydelig tver- 
gaaende Sutur (se Fig. 3), der ender til hver Side 
med et lidet sterkt chitiniseret Fremspring, hvortil 
Kindbakkernes ovre Ende er articuleret. Den dor- 
sale Del af Segmentet er sterkt hvelvet og nesten 
af samme Leengde som Hovedet, hvorimod den ven- 
trale Del er meget kort og kun indskrenket til 
Mellemrummet. mellem Kindbakkerne og Skallens 
Tmkkemuskel. 
Den egentlige Krop (truncus) (se Fig. 1) er over 
dobbelt saa lang som de 2 foregaaende Afsnit til- 
sammen og nesten cylindrisk af Form, eller kun 
ganske syagt afsmalnende bagtil. Den er delt i en 
Rekke meget uniforme Segmenter, hvert berende et 
Par Branchialfodder. Antallet af Segmenter er hos 
fuldvoxne Individer, i Overensstemmelse med Bran- 
chialfoddernes Tal, 22—24, hvoraf dog det bagerste 
sedvanligvis er ufuldkomment sondret. Alle Seg- 
menter, med Undtagelse af de allerforreste, har 
oventil et Knippe af bagudkrummede Borster, mest 
udviklede paa de bagerste Segmenter. Nogen tyde- 
12 — G. 0. Sars: Fauna Norvegiz. 
89 
on the under side in the form of the labrum. On 
the boundary between the head and the cervical 
segment lie the 2 powerful mandibles, and immediately 
behind them on the ventral side, the 2 pairs of 
maxille. The trunk carries from 22 to 24 pairs of 
branchial legs, and is divided into a corresponding 
number of very uniform segments. The caudal sec- 
tion is without any true limbs, but carries at the 
extremity 2 strong, movable claws, and dorsally 2 
small, juxtaposed bristles. 
I will now pass on to describe each of these 
sections more fully. 
The head (see Pl. XV, figs. 2, 3, 4) is of com- 
paratively small size, and, seen from the side (fig. 2), 
of an irregular, triangular shape. Its dorsal surface 
is evenly convex, and carries in the middle a pecu- 
liar, stalked, somewhat club-shaped appendage (af) 
which is usually interpreted as an organ of attach- 
ment. The frontal part is very prominent, almost 
conically drawn out, and ending in a blunt point, 
within which the compound eyes are situated. Below 
the frontal part, the head has a deep angular inden- 
tation, whereby the frontal part is very sharply 
divided from the triangularly projecting rostrum. 
The latter is somewhat triangular in section, having 
above a sharp edge, while below it is slightly hol- 
lowed out along the middle. The bottom of the 
groove appears, when the head is seen from the 
side, like a curved line extending from the point of 
the rostrum backwards towards the base of the 
labrum. Seen from above (fig. 3) or from below 
(fig. 4), the head looks rather broad at the back, but 
tapers rapidly in front towards the narrowly rounded 
frontal part. 
The cervical segment is separated above from 
the head by a very distinct and rather deep hollow, 
at the bottom of which may be traced a dis- 
tinct transverse suture (see fig. 3) ending at each 
side in a highly chitinised process, to which the 
upper ends of the mandibles are articulated. The 
dorsal part of the segment is considerably vaulted, 
and of almost the same length as the head, the 
ventral part, on the other hand, being very short, 
and confined only to the space between the man- 
dibles and the adductor muscle of the shell. 
The body proper (trunk) (see fig. 1) is more 
than twice as long as the 2 preceding sections 
together, and almost cylindrical in shape, or only 
very slightly tapering behind. It is divided into a 
series of very uniform segments, each bearing a 
pair of branchial legs. The number of segments in 
full-grown individuals corresponds with the number 
of branchial legs, viz from 22 to 24, of which, 
however, the hindmost is generally imperfectly 
defined. All the segments, with the exception of 
the very foremost ones, have a bunch of backward- 
curved bristles above, those on the hindmost seg- 
