lOo 



tvdeligt soiidrptle, idet der melleiii dem og.saa d(ir- 

 salt er eii temmelig dyb Indbiigtiiing. Hovedet er 

 jæviit iivælvet civentil og afrundet fortil, med et 

 stumpt Fremspring nedenfor det enkle Øie, forestil- 

 lende Anlægget til Rostrum. Umiddelbart bag dette 

 Fremsj)ring sees de endnu knudeformige Iste Par 

 Fulere at tidgaa. Bag disse igjen rager den enormt 

 udviklede Overlæbe frem, med sin skraat nedad- 

 rettede pigformige Fndefortsats. Ved dennes Basis 

 er der indad en liden ciliex'et Lap, der sædvanligvis 

 er Ijoiet ind mod Mundaabningen og som svarer til 

 (len verticalt stillede Endelamelle hos det voxne 

 Dyr. Til hver Side af Mundaabningen sees de nu 

 vel udviklede Kindbakker, fra hvis ydre Side Man- 

 dibularfodderne udgaar, og umiddelbart liag dem 

 igjen viser sig Anlægget til de 2 Par Kjæver. Ityg- 

 skjoldet har nu udviklet sig til en kappefoi'mig 

 Hnddnjilieatiir, bestaaende af 2 symetriske Halvdele 

 skilte bagtil i Midten ved en dyb Indbugtning. 

 Det har nu tydeligt sondret sig ogsaa fortil; men 

 de 2 Halvdele gaar ganske umærkeligt over i hin- 

 anden dorsalt, uden at der endnu er nogen tydelig 

 Sondring af 2 Valvler. De sig udvikleiule Fodder, 

 der nu fuldstændig dækkes oventil af Rygskjoldet, 

 har forlænget sig til noget polseformige Fortsatser, 

 der er rettede skraat bagtil og ligger tæt sammen. 

 I)en bagerste Del af Kroppen er ganske svagt om- 

 boiet mod Bugsiden og begynder at sondre sig som 

 en tydelig Haledel. De terminale Fortsatser viser 

 sig nu klarlig at være identiske med de senere be- 

 vægeligt til Enden af Haledelen indleddede Hale- 

 klor. 1 nogen Afstand fra dem ])aa Dorsalsiden har 

 allerede Haleliorsterne udviklet sig; derimod er der 

 endnu ikke noget Spor af de for det voxne Dyr 

 eharacteristiske tandede Hale]ilader. Af de For- 

 andi'inger, der er foregaaet med den indre Organi- 

 satidu kan nævnes, at de i tidligere Stadier simple 

 blindsækformige Udvidninger af Tarmens forreste 

 Del har hver sondret sig i en dorsal og en ventral 

 Jja]), og at Hjertet har dannet sig i den forreste 

 Del af Trnncus. 



Sidste Lar\('stadium er fremstillet Fig. 7. fra 

 Rygsiden. Legemet har nu en Længde af 1,14 mm. 

 og ligner idethele samme hos de 2 foregaaende Sta- 

 dier, dog med den Forskjel, at Hovedets Pandedel 

 er noget mere frems])ringende, og at Kygskinldct 

 er lietydelig storre. Dette sidste divkker nu som 

 en bred Kappe Storsteparten af Truncus tilligemed 

 de til samme horende Lemmer oventil og har bagtil 

 et dybt Indsnit. Fodderne, hvis Antal frenuleles 

 kun er II l*ar, er endnu fuldsta^ndig uljevtvgelige, 

 men har nu sondi-et sig i sine respective Hoved- 

 afsnit, iiv(jraf na\nlig K]ii|ioditeriie er meget tyde- 

 lige i Dyrets dorsale Stilling. Fra Enderne af Fod- 

 derne er allerede korte l)orster begyndt at spire 



14 — (i. 0. Sårs: Fauna .Vorir.aia'. 



verv distinctly defined, as there is, dorsally too, a 

 rather deeji IioUdw between them. The liead is 

 evenlv arched above and rounded in front, with a 

 blunt projection below the ocellus, representing the 

 rudiment of the rostrum. Immediately behind this 

 projection, the still nodiform 1st pair of iintennæ 

 are seen to issue. Behind them again, ])rojects the 

 enormously develojied labrum, with its sjiiniform 

 terminal protuberance directed obli([uely downwards. 

 At its base inside, there is a little ciliated lolje, 

 which is usually bent in towards the oral apei'tui'e, 

 and which corresjjonds to the vertically-i)laced ter- 

 minal lamella in the full-grown animal. On each 

 side of the (U'al aperture are seen the now well- 

 developed mandibles, from the outer side of whicli 

 issue the mandibular legs, and immediately behind 

 them again, appear the rudiments of the 2 pairs of 

 maxillæ. The cara])ace has now developed into a 

 hood-.shaped cuticular dujilicature, consisting of 2 sym- 

 metrical halves, separated l)eliind in the middle by a 

 deep depression. It has also become well defined 

 in front, but dorsally the two halves run quite 

 imperceptibly into one anotlier, without as yet any 

 distinct division into 2 valves. The develojjing legs, 

 which are now comjjletely covered above by the. 

 carapace, have lengthened into somewhat sausage- 

 shaped protuberances, directed obliquely backwards, 

 and lying close together. The hinder part of the 

 body is very slightly bent down towards the ventral 

 surface, and begins to be marked otf as a distinct 

 cai;dal part. The terminal ju-qjections now show 

 themselves (dearly to be identical with the caudal 

 claws subseiiueiitl\- iii(ivabl\' articulated t" the end 

 of the caudal section. At simu' distance iVoni them 

 on the dorsal side, the caudal bristles have already 

 developed, whereas there is as yet no trace of the 

 dentated caudal lamellæ characteristic of tiie adult 

 animal. Among the changes that have occurred in 

 the internal organisation, it may be mentioned that 

 the simple cæcal expansions of the front part of the 

 intestine in eai'lier stages, have become marked otl' 

 into a dorsal and a ventral lobe, and that the heart 

 has been formed in the anterior part of the trunk. 

 In fig. 7. the last larval stage is represented, 

 seen from the ventral surface. The body now has 

 a length of Ll-t mm., and on tiie whole resembles 

 that in the 2 ])receding stages, though with these 

 differences, viz., tliat the frontal part of the head 

 is rather more prominent, and that the carapace is 

 considerably larger. Tiie latter now covers like a 

 broad mantle the upper jiortion of the greater part 

 of the trunk and limits, and has a deep emargina^ 

 tion behinil. The legs, which still only numlter li 

 pairs, are as yet ([uite immovable, but are now divided 

 into their res])ective principal pai'ts, of which no- 

 taldv the epipodites are ver}- distinct in the ani- 

 mal's dorsal position. From the extremities of the 



