122 
af Hovyedet opover, vil man helt bagtil, i nogen 
Afstand fra den tvergaaende Sutur, der skiller Ho- 
vedet fra Nakkesegmentet, bemerke en liden grube- 
formig Fordybning (Fig. 11, x), der constant fore- 
kommer her hos alle Individer, baade Hanner og 
Hunner. Ifolge sin Plads maa denne Grube ner- 
mest ansees for homolog med Fastheftningsorganet 
hos Limnadia, skjondt det er lidet troligt, at denne 
ubetydelige Grube kan her fungere som et saadant 
Organ. 
Forste Par Folere (Fig. 11, a1, Fig. 2), .som er 
feestede til hver Side af Hovedets ventrale Del, 
umiddelbart foran Basis af Overleben, er meget 
smaa og af noget kelledannet Form. De bestaar 
hver af et kort Skaft og en noget buet, i sit ydre 
Parti fortykket Endedel, der fortil er tet besat med 
delicate Lugtepapiller (Fig. 2a); af et lignende Ud- 
seende som hos Limnadia. Disse Folere er til en 
vis Grad bevegelige ved Hjelp af en Del smaa 
Muskler, som passerer til dem fra Hovedets Inte- 
gument. 
Andet Par Folere, eller Aarerne (Fig. 3), ud- 
springer, som hos Limnadia, med en bred Basis fra 
Hovedets Sider, umiddelbart under den bagre, mest 
fremspringende Del af Fornix. De bestaar af de 
samme Dele som hos. Limnadia, nemlig et tykt, 
eylindriskt Skaft, og 2 Grene; men disse sidste er 
her paa langt ner ikke saa steerkt forleengede som 
hos hin Slegt. Skaftet, hvis basale Del synes at 
vere fuldstendig ubeveegelig, er derimod paa Midten 
meget boieligt og her delt i flere korte, tildels ufuld- 
steendigt sondrede Led, medens dets ydre Trediedel 
danner et enkelt Led for sig. Fra Basaldelen ud- 
gaar bagtil et Antal af omkring 5 sterke nedad- 
rettede Fjzrborster, og i Forkanten af det yderste 
af de mediane Led er der en Del grove Pigge, ord- 
nede i en Tverrad. En lignende Tverrad af Pigge 
findes ogsaa ved Enden af Skaftet fortil. Grenene 
er neppe lengere end Skaftet og omtrent af ens 
Storrelse, eller den bagre ubetydeligt lengere end 
den forreste. De er begge delte i et stort Antal 
(fra 15 til 18) korte Led, der dog ved Basis af Gre- 
nene er meget utydeligt sondrede. Ethvert Led har 
i Bagkanten en enkelt lang Svommeborste, og paa 
den forreste Gren har de fleste Led endnu hvert en 
enkelt steerk Pig i den modsatte Kant. Sidste Led 
har paa den bagre Gren 2 Svommeborster, paa den 
forreste desforuden en Pig. Naar Aarerne er i 
Hvile, legges de almindeligvis. langs ad Siderne af 
Hovedet, umiddelbart bag. dettes laterale Kjole. De 
fra Hovedets Integument til Aarerne gaaende Musk- 
ler er meget kraftige og fester sig alle ved det 
midterste boielige Parti af Skaftet. I dettes ydre 
Del sees andre Muskler, der virker paa enhyer af 
Grenene. ; 
| 
the dorsal margin of the head upwards, there 
is observable, at the very back, at some distance 
from the transverse suture, which separates the 
head from the ceryical segment, a small pit-like 
depression (fig. 11, z), which occurs invariably in all 
specimens, both males and females. From its place, 
this pit must probably be regarded as homologous 
to the organ of attachment in Limnadia, although 
it is almost incredible that this insignificant hollow 
can here act as such an organ: 
The Ist pair of antenne (fig. 11, a’, fig, 2) which 
are attached to the sides of the ventral portion of 
the head, immediately in front of the base of the 
labrum, are very small, and of a somewhat clavate 
form. They each consist of a short scape, and a 
somewhat curved terminal part, thickened in its 
outer portion, and thickly set in front with delicate 
olfactory papille (fig. 2a), of an appearance similar 
to those in Limnadia. These antenne are movable 
to a certain extent by the aid of several small 
muscles passing to them from the integument of 
the head. 
The second pair of antenne, or the oars (fig. 3) 
issue, as in Limnadia, with a broad base from the 
sides of the head, immediately below the hinder, 
most projecting part of the fornix. They consist of 
the same parts as in Limnadia, namely a_ thick, 
cylindrical scape, ‘and 2 rami; but the latter are 
here not nearly so much elongated as in the before- 
mentioned genus. The scape, of which the basal 
part appears to be quite immoyable, is, on the 
other hand, very flexible.in the middle, and is here 
divided into seyeral short, to some extent imper- 
fectly defined joints, while its distal third . part 
forms a single joint by itself. From the basal part 
there issue at the back about 5 strong, downward- 
pointing plumose sete, and on the anterior margin 
of the most distal of the median joints, there are-a 
number of coarse spines arranged in a transverse 
row. A similar transverse row of spines is also 
found at the end of the scape in-front. The rami 
are scarcely longer than the scape, and are of 
almost equal size, the hind one being very slightly 
longer than the front one. They are both divided 
into a great number (from 15 to 18) of short joints, 
which, however, are very. indistinctly defined at. 
the base. On the hind margin: of. each joint, there 
is a single long natatory bristle, and on the front 
ramus, most of the joints have, yet another single, 
strong spine on the opposite margin. On the hind 
ramus there are 2 natatory bristles on the last 
joint, and. on the front..ramus, a spine as _ well. 
When. the oars are at rest, they generally. lie 
along, the sides of the head, immediately behind its 
lateral keel, - The muscles running from. the integu- 
ment of the head to the oars are very powerful, 
and are all attached to the middle,, flexible: iis of. 
