00 



skaarne i Kanterne (ly delvis forsynede med korte 

 Borster. Bag disse 7 Par Lemmer sees endnu 2 Par 

 smaa Tværvnlster, hvorved disse Lemmers Autal er 

 steget til 9 Par. Endnu mangler imidlertid ethvert 

 Spor til de 2 sidste Par, som forst senere anlægges 

 paa samme Maade som de ovrige. Bagkroppen er 

 endun ganske kort og uleddet. Dens Endelapper 

 har sondret sig fra Haleenden og bærer nu hver 3 

 borsteformige Vedhæng, hvoraf det midterste er be- 

 tvdelig storre end do 2 ovrige. 



Fig. 17 fremstiller den forreste Del af Legemet 

 hos et lidt senere Larvestadium, seet nedenfra og 

 noget stærkere forstorret. De sammensatte Øine (o) 

 har tiltaget betydelig i Storrelse og viser sig alle- 

 rede kort stilkede, med Øienglolien vel udviklet. 

 Iste Par Folere (a') er paa det nærmeste uforan- 

 drede. 2det Par Folere (a-) synes forholdsvis min- 

 dre, idet de er bleven staaende paa samme LTdvik- 

 lingstrin, medens de Heste ovrige r)ele er tiltaget i 

 Størrelse. Det samme gjælder ogsaa Mandibular- 

 fødderne (p). som i Forhold til selve Kindbakkernes 

 Corpus (M) synes meget reducerede. Overlæben (L) 

 er fremdeles meget stor og fx-emragende. De 2 Par 

 Kjæver er allerede tydeligt udviklede og forsynede 

 med en Del Borstei'. Alle Branchialfodder er mr 

 anlagte, men de 2 liagerste Par endnu kun tilstede 

 som ubetydelige Tværvulster. 



Fnder den videre U(hikling sondrer Anlægget 

 til de 2 bagerste Par Braiu'hialfodder sig fra Krops- 

 siderne som tydeligt fremragende Lemmer, Halen 

 strækker sig i Længden og bliver, som det ovrige 

 Legeme, tydeligt segmenteret, samtidigt med at 

 Halepladerne mere tydeligt afgrændser sig og faar 

 et storre Antal Borster. 2det Par Folere reduceres 

 mere og mere, men beholder dog endnu en Tid lang 

 sine Svommeborster og bevæges som hos de vngre 

 Larver. Mandibularfodderne svinder mere og mere 

 ind (ig er tilsidst kun tilstede som rudimentære Ved- 

 hæng. Larven, som paa dette Stadium har en Længde 

 af omtrent ;"> mm, staar nu paa (Overgangen til at 

 antage den blivende Tilstand. Den er afbildet paa 

 dette Udviklingstrin Tab. VI, Fig. f) og li. Ved den 

 derpaa følgende Hudskiftning er Larvetilstanden 

 forln, idet det sidste Spor af Mandibularfoddeime er 

 forsvundet og 2det Par Folere har tal)t sin Betyd- 

 ning af Lokoiiiotionsorganer. Endnu er der dog paa 

 de sidstnævnte Lemmer (se Fig. 7 og 8) en tydelig 

 Adskillelse mellem Skaft og Grene. Den ydre Gren 

 ender i en noget bngtet Spids. paa hvilken endnu 

 de sidste svage Rester af de oprindelige Svomme- 

 borster sees (Fig. 8) ; Indergrenen ser ud som et 

 yderst lidet knudeformigt Fremspring, uden enhver 

 Borstebeklædning. Er Uno-en Ijestemt til at blive 



sides of tlir bod\', and [imject perceptibly in tlip 

 form of curved lamellæ, slightly indented and 

 with the edges partially furnished with liristles. 

 Behind tiiese 7 jiairs of limbs, 2 more pairs of 

 small transverse prominences are vi.sible, rai.sing 

 their number to 'J pairs. All trace, however, of 

 the last 2 jiairs is still alisent, and it is only 

 later that they commence in the same way as the 

 others. The hind part of the liody is still ijuite 

 short and inarticulated. Its terminal lobes have 

 become separated from the caudal end, and now 

 each carry 3 setiform appendages, the middle one 

 of whicli is considerably larger than the ntlier two. 



Fig. 17 represents the antei'ior part of the body 

 in a somewhat nmre advanced larval stage, seen 

 from below, and rather strongly magnified. The 

 compound eyes (o) have increased consideraldy in 

 size, aiul alreadj' have short pedixncles. while the 

 eye-ball is well-develojied. The 1st jiair of antennæ 

 (a ') are nearly unchanged. The 2nd pair of antennæ 

 (a-) seem to be comparatively smaller, having re- 

 mained at the same developmental stage, while most 

 of the other parts have increased in size. The same 

 applies to the mandibular legs (p), which, in relation 

 to the body of the nmndible (M), seem very miTch 

 reduced in size. The lal)rum (L) is still very large 

 and jirojecting. The two pairs of maxillæ are al- 

 ready perceptibl^• developed, anil furnished with a 

 few bristles. All the branchial legs have now ap- 

 peared, but the hindmost 2 pairs still only as insig- 

 nificant transverse prominences. 



During further dei,-elo])me]it the I'udiments of 

 the hindmost 2 i)airs of firanchial legs separate 

 themselves from the sides of the body as distinctly 

 projei'ting lindis. The tail is elongated and becomes, 

 like the rest of the body, perceptibly articulated, 

 while, at the same time, the caudal lamellæ are 

 more distinctly defined, and have ac(|uired a larger 

 number of Ijristles. The second pair of antennæ be- 

 come more and more reduced, but still for some 

 time retain their natatory bristles, and are nuived 

 as in the younger larvæ. The mandibular legs 

 dwindle more and more, and at last only appear as 

 rudimentary appeiulages. The larva, which, at this 

 stage, has a length of about 5 mm, is on the jioint 

 of entering its permanent condition. It is tlius re- 

 presented on PI. VI, figs, f) and I!. With the en- 

 suing exuviation, the larval period is past, the last 

 trace of mandilnilar legs having vanished, and the 

 2nd jiair of antennæ having lost their importam/e 

 as organs of locomotion. In the last-named limbs 

 (see figs. 7 and 8) there is still, however, a di.stinct 

 separation between the scape and the rami. The 

 outer ramus ends in a somewhat curved jjoint, upon 

 which the last feeble remains of the original nata- 

 tor}^ bristles are visible (fig. 8). The inner ramus 

 looks like an extremely small nndifurm ])rojection. 



