Sidefladerne af Hovedet (se Tab. XV, Fig. 1), og 
bestaar hver af et cylindriskt, muskulost Skaft og 
2 sterkt forlengede Grene. Skaftet viser ved Basis 
en noget albuformig Boining og er her i Bagkanten 
forsynet med et lidet borstebesat Fremspring (se 
ogsaa Fig. 3, a*). Dets ydre Del er meget boielig 
og delt i omtrent 8 korte Segmenter tet besatte 
fortil med sterke, pigformige Borster. Grenene er 
meget smale og af meget betydelig Lengde, navnlig 
den indre eller bagre, der er over dobbelt saa lang 
som Skaftet. Begge Grene er delte i talrige (fra 
1U til 14), meget skarpt afsatte og noget skivefor- 
mige Led, hvoraf hvert i Bagkanten har flere lange, 
2-leddede og fint cilierede Svommeborster, i Forkan- 
ten ligeledes et storre Antal af sterke, i Enden 
noget hageformigt krummede Pigge. Saavel Grene- 
nes indbyrdes Leengde som Antallet af Led paa hver 
Gren er forovrigt noget varierende hos forskjellige 
Individer. 
Overleben (Tab. XV, Fig. 2, 4, £, Fig. 7) ud- 
gaar bagtil som den umiddelbare Fortsettelse af 
Hovedets ventrale Del, og hvelver sig paa Under- 
siden ud over Kindbakkernes Tyggedel, samt naar 
med Spidsen ind mellem Basis af Iste Fodpar (se 
Fig. 1). Den er imidlertid til en vis Grad bevege- 
lig, idet den ved to tynde til dens Basis lobende 
Muskler kan loftes noget af fra Munddelen og igjen 
ved andre Muskler presses tet ind mod samme. Af 
Form er den nesten halveylindrisk, med den nedad- 
vendte Flade sterkt convex, den ovre noget concav. 
Ved Enden indsneevres den pludselig, dannende til 
hver Side et vinkelformigt Hjorne, og forlenger sig 
til en meget boielig og i Enden fint cilieret Spids. 
Ovenover denne tentakelformige Fortsats har den 
en skiveformig, lodret stillet Endelamelle, der leg- 
ger sig ind mellem de 2 Par Kjever, naar Over- 
leben presses ind mod Legemet. I Overlebens indre 
sees flere celleagtige Legemer, der synes at vere 
af kjertelagtig Natur, og ligeledes et storre Antal 
tveergaaende Muskler, der virker paa den blode ovre 
Flade og rimeligvis har Betydning ved Svelgnings- 
processen. 
Kindbakkerne (Tab. XV, Fig. 2, 3,4, 1, Fig. 8), 
der som 2 Boiler omfatter Siderne af Legemet paa 
Grendsen mellem Hovedet og Nakkesegmentet, er 
meget kraftigt udviklede og hos det voxne Dyr uden 
ethvert Spor af Palpe. Den spidst udlobende ovre 
Ende af det baadformige Corpus er beveegeligt arti- 
culeret med en liden knopformig Fortykkelse af 
Integumentet ved hver Ende af den Tversutur, som 
findes i Bunden af den dorsale Indbugtning mellem 
Hovedet og Nakkesegmentet. Tyggedelen er steerkt 
indbgiet og sondret fra Corpus ved en tydelig Ind- 
knibning eller Hals. Den ender, som hos Branchi- 
podiderne med en bred, fint riflet Tyggeflade uden 
92 
from the lateral surfaces of the head, with a broad 
base (see Pl. XV, fig. 1), and each consist of a 
cylindrical, muscular scape, and two greatly elon- 
gated rami. The scape exhibits at the base a some- 
what elbow-like bend, and on the hind margin at 
this point, is furnished with a little setous projec- 
tion (see also fig. 3, a’). Its distal part is very 
flexible, and divided into about 8 short segments, 
thickly clothed in front with strong spiniform brist- 
les. The rami are very narrow, and of considerable 
length, notably the inner or hinder one, which is 
more than twice as long as the scape. Both rami 
are divided into numerous (from 10 to 14) very 
clearly defined and somewhat lamellar joints, each 
of which has several long, bi-articulated and finely 
ciliated natatory bristles in the hind margin, and a 
large number of strong, rather hamous spines in 
the front margin. Both the mutual length of the 
rami, and the number of joints in each ramus, varies 
somewhat in different specimens. 
The labrum (Pl. XV, figs. 2,4, Z, fig. 7) projects 
backwards as the immediate continuation of the 
ventral part of the head, and on its inferior side 
arches over the masticatory part of the mandibles, 
its point extending in between the base of the first 
pair of legs (see fig. 1). To a certain extent, how- 
ever, it is movable, for it can be raised a little 
from the oral parts by two thin muscles running to 
its base, and again, by other muscles, can be pressed 
close in against those parts. In shape, it is almost 
semi-cylindrical, with the down-turned surface very 
convex. At the extremity it is suddenly contracted, 
forming on each side a sharp corner, and being 
produced to a very flexible point, finely ciliated at 
the extremity. Above this tentacular projection 
there is a discoid, vertically-situated, terminal 
lamella, which is interposed between the 2 pairs of 
maxille, when the labrum is pressed in towards 
the body. In the interior of the labrum are visible 
several cell-like bodies, which appear to be of a 
glandulous nature, and also a large number of 
transverse muscles, which act upon the soft upper 
surface, and probably perform a part in the process 
of swallowing. 
The mandibles (Pl. XV, figs. 2, 3, 4, M, fig. 8) 
which embrace the sides of the body like 2 bows, 
on the boundary-line between the head and the cer- 
vical segment, are very powerfully developed, and, 
in the full-grown animal, without a trace of palpi. 
The pointed upper end of the boat-like body is 
movably articulated with a small bud-like thickening 
of the integument at each end of the transverse 
suture found at the bottom of the dorsal hollow 
between the head and the cervical segment. The 
masticatory part is very much incurved, and sepa- 
rated from the corpus by a distinct constriction or 
neck. It ends, as in the Branchipodide with a 
