29 



Segmenter, og Halegrenene er tydeligt afsatte samt 

 liver i Spidsen forsj'iiet med en kort Borste. Pande- 

 pladen (R) er nu tj^deligt fremragende, og Øienstil- 

 kene (0) har antaget en noget konisk Form samt 

 viser i sin ydre Del den første svage Antydning til 

 Dannelse af Synselementer. Til hver Side af Tar- 

 men bemærkes i Midtkroppen en temmelig plump 

 og kort cylindrisk Sæk, der aabenbart forestiller en 

 af Leversækkene. Den dorsale Del af Forkroppen 

 er endnu stærkt opblæst og fyldt af rcdgul Blomme- 

 masse. Umiddelbart nedenfor denne Del sees nu 

 tydeligt de frie Kanter af Rygskjoldet. De Foran- 

 dringer, Embryonet endnii har at gjennemgaa, er 

 ganske successive. Den tilbageværende Rest af 

 Blommemassen opbrviges lidt efter lidt, og samtidigt 

 aftager den dorsale Opsvulning af Hovedet i Stør- 

 relse, medens Rygskjoldets Val vier mere og mere 

 voxer Ild over Siderne af Midtkroppen. De forskjel- '■ 

 lige Ivropsvedhæng udformes og indtager den for 

 dem characteristiske Stilling i Forhold til Legemet, 

 hvorved ogsaa meget snart Nebalia-Habitusen bliver 

 fremtrædende. Fig. 12 fremstiller Ungen, naar den 

 er færdig til at forlade Klækkehulen. Man har 

 ingensomhelst Vanskelighed med i den at erkjende 

 en ung Nebalia. Den eneste væsentlige Afvigelse 

 er, at der fremdeles kun er 3 Par Svømmefodder 

 tilstede. Af det 4de Par sees kun et ubetydeligt 

 Anlæg bag de øvrige, i Form af et Par smaa knude- 

 formige Fremspring (pM. Ungen kan nu bevæge sig 

 frit i Våndet og ernære sig selv; men det varer 

 endnu adskillig Tid, inden de forskjellige Vedhæng 

 opnaar sin fulde Udvikling og faar sin normale rige- 

 lige Borstebesætning. Af alle Vedhæng er 4de Par 

 Svommefødder de, som udvikler sig senest. 



appendages of the body are all freely projectant, 

 while, also, the segmentation of the body is distinct 

 externalh'. The dorsal curvature of the embryo is 

 now so great, that the body almost describes a com- 

 plete semi-circle. The appendages pertaining to the 

 head have considerably increased in size, Init are 

 otherwise only little changed. Still there may be 

 noted on the foremost pair (a') a little sub-branch that 

 indicates the lamelliform appendage. The branchial 

 feet (brp) are present in their full number (8 pairs) 

 and show themselves to be all deeply fissured 

 and directed straight downwards. On the other 

 hand, there are as yet only found 3 pairs of swim- 

 ming feet (pi) in a rudimentary state, as the 4tli 

 pair only much later becomes developed. Neither 

 is there any trace of caudal feet observed. The 

 urosome itself has now, however, its full number 

 of segments, and the caudal rami are distinctly 

 projected and each furnished with a short bristle at 

 the tip. Tiie frontal plate (R) is now distinctly 

 projectant, and the ocular stems have now assumed 

 a somewhat conical form and in their external part 

 exihibit the first faint indication of the formation 

 of visual elements. In the mesosome, on each side 

 of the intestine, there is noticed a pretty stout 

 and short cylindrical sac, which evidently represents 

 one (if the liver sacs. The dorsal part of the an- 

 terior body is still greatly blown out and filled with 

 red-yellow yolk substance. Immediately below that 

 part the free edges of the carapace are now dis- 

 tinctly seen. The changes that the embryon has 

 yet to undergo are quite successive. The remains 

 of the yolk substance are little by little used 

 u]), and the dorsal swelling of the head becomes 

 at same time reduced in size, while the valves 

 of the carapace grow more and more out over the 

 sides of the mesosome. The various appendages 

 of the body become fully formed and occupy the 

 characterstic position in relation to the body pe- 

 culiar to them, causing thus the Nebalia habitus 

 A^ry soon to become prominent. Fig. 12 represents 

 the 3'oung one when it is ready to abandon the 

 hatching cavity. We have no difficulty whatever, 

 in recognizing in it a young Nebalia. The only 

 material divergence is, that there are still only 

 3 pairs of swimming feet present. Of the 4th pair 

 there is only seen a faint rudiment behind the 

 others, in the shape of a pair of small nodular 

 prominences (p'). The young one can now move 

 itself freely in the water, and nourish itself; but 

 some time still jjasses, before the various appendages 

 attain their full develophient and acquire their nor- 

 mal, abundant bristle-covering. Of all the append- 

 ages, the 4th pair of swimming feet are those which 

 develope themselves latest. 



