a 
sette sine Aig, hvad der sikrer Artens fortsatte 
Existens, om Forholdene et andet Aar skulde vise 
sig gunstige for en ny Generations Udvikling. Som 
Regel synes det dog at vere et meget lidet Procent- 
tal af de utallige Larver, som i Begyndelsen ud- 
klekkes, der virkelig kommer til fuld Udvikling. 
Larver og Unger finder man uden Forskjel overalt 
i de Vandansamlinger, hvori de treffes, lige saa 
hyppigt tet inde ved Bredden som ude paa dybere 
Vand. Anderledes er det med fuldvoxne Exempla- 
rer. Disse holder i Regelen kun til paa de dybeste 
Steder af“ Dammen og her gjerne ner Bunden. Da 
Dyrene i Regelen er meget gjennemsigtige, er det 
ikke saa godt at faa Die paa dem fra Stranden af. 
Dog vil ialmindelighed den opake gulbrune Ag- 
masse forraade dem, navnlig naar Bunden, henover 
hvilken de beveger sig, bestaar af morkt Mudder. 
Bevegelsen er ikke synderlig hurtig og har Cha- 
racteren af et forholdsvis sagte og noget ujevnt 
Lob, hvorunder i Regelen Ryggen vender opad. 
Holdte i Aquarier kan man noiere studere deres 
Bevegelser og ovrige Levevis. Der kan ikke vere 
nogen Tvivl om, at Dyrets hovedsageligste Be- 
veegelsesorganer er Aarerne. Det er ved hurtigt 
gjentagne Slag til Siderne af disse Lemmers ydre 
Parti, at Legemet bliver drevet igjennem Vandet, 
skjondt ogsaa Branchialfoddernes Svingninger tor 
til en vis Grad understette Bevegelsen. Stoder 
Dyret under sine Bevegelser paa tette Conferve- 
masser, formaar det med stor Behendighed at ar- 
beide sig igjennem dem, hvorved den meget beveege- 
lige Bagkrop spiller en vigtig Rolle. Idethele sees 
Dyret meget ofte at foretage energiske Boininger 
og Strekninger af denne Del af Legemet, dels for 
at overvinde Hindringer for dets Passage gjennem 
Vandet, dels for at befri det indre af Skallen for 
fremmede indkomne Partikler. Meget ofte faar man 
se, at Dyret med Forenden hefter sig fast til de i 
Vandet verende Gjenstande, navnlig til Undersiden 
af Blade eller Conferver i Overfladen af Aqvarierne, 
og forbliver i denne Stilling sedvanligvis i lengere 
Tid. Fastheftningen synes hovedsageligst at tilveie- 
bringes ved de sterke hageformige Pigge langs For- 
siden af Aarernes Grene, tildels ogsaa ved det eien- 
dommelige fra Hovedets Dorsalside udgaaende kolle- 
formige Appendix, som man ved noiere Undersogelse 
altid vil finde er i umiddelbar Contact med den 
Gjenstand, hvortil Dyret er fastklamret. Dyret er 
herunder ikke i absolut Ro, men der foregaar en 
svag rhytmisk Svingning af hele Legemet frem og 
tilbage, aabenbart foraarsaget ved de heftigt beve- 
gede Branchialfodder. Disse Svingninger sker paa 
fuldkommen samme Maade som hos Branchipodiderne, 
idet de ikke er simultane men successive, hvad der 
giver Indtrykket af en eiendommelig grazios Undu- 
lation i Bevegelsen. Idethele er det meget sjelden 
at denne svingende Bevegelse af Branchialfodderne 
| some, at any rate, of the animals attain to sexual 
maturity, and are able to deposit their eggs, thereby 
ensuring the continued existence of the species, 
should conditions another year be favorable for the 
development of a new generation. As a rule, it 
appears to be a very small percentage of the innu- 
merable larve at first hatched, that really become 
fully developed. Larve and young ones are found 
without distinction all over the pieces of water in 
which they are met with, quite as frequently close 
to the bank as out in deeper water. It is otherwise 
with fullgrown animals. They generally keep to 
the deeper parts of the pond and near the bottom. 
As the animals are generally very transparent, it 
is not very easy to see them from the shore. The 
opaque, yellowish brown mass of eggs, however, will 
generally betray them, especially if the bottom, 
over which they move, consists of dark mud. The 
motion is not remarkably quick, but has the cha- 
racter of a comparatively slow and somewhat 
uneven dart, during which the back is generally 
uppermost. When kept in an aquarium, its move- 
ments and other habits may be more carefully stu- 
died. There can be no doubt that the animal's 
most important organs. of locomotion are the oars. 
It is by quickly repeated side-strokes of the 
distal part of these limbs that the body is driven 
through the water, although the swinging of the 
branchial legs may also, to a certain extent, assist 
the movement. Should the animal, as it moves, 
come in contact with thick masses of conferve, it 
manages with great dexterity to work its way 
through them, the very mobile hind part of the 
body playing an important part in that proceeding. 
The animal may often be observed to make ener- 
getic bends and extensions of this part of the body, 
partly to overcome obstacles to its passage through 
the water, partly to rid the shell of foreign par- 
ticles that have entered. The animal may very 
often be seen to attach itself by its anterior end 
to objects in the water, especially to the under 
surface of leaves or confervee on the surface of the 
aquarium, and generally remain in this position for 
some time. The attachment appears principally to 
be effected by means of the strong, hook-like spines 
along the front of the rami of the oars, and partly 
by the peculiar clavate appendage issuing from 
the dorsal surface of the head, and which, on close 
examination, will always be found in immediate 
contact with the object to which the animal is 
clinging. The animal meanwhile is not absolutely 
at rest, for there is a slight rhythmical swinging 
to and fro of the whole body, occasioned by the 
violent agitation of the branchial legs. These pul- 
sations take place in exactly the same manner as in 
the Branchipodide, not being simultaneous but suc- 
cessive, thus producing the impression of a peculiar, 
EO 
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