54 



fjernet og nærmet til Mundaabningen og Itidrager 

 derved til Fodens Optagelse. Af de 2 (xrene ei- den 

 indre ganske kort, cylindrisk og forsynet paa- Spid- 

 •sen med 4 cilierede Børster. Den ydre (Iren er der- 

 imod af Ijetydelig Storrelse, omtrent saa lang som 

 Skaftet og temmelig tyk, dog gradvis afsmalnende 

 mod Enden. Den er meget boielig og vii^er en An- 

 tydning til en tæt Leddeling, idet Kanterne er fint 

 crenulerede. Langs ad dens indre Side lindes en 

 Rad af 15 — 16 stæi"ke, cilierede Svommeborster, 

 hvoi'af 2 udgaar fra selve Spidsen. — Uverlæben er 

 meget stor og fremspringende, dannende en oval, i 

 en stump Spids endende og i Flugt med Hovedets 

 undre Flade gaaende Klap, der gan.ske dækker 

 Mundaabningen nedad. — Kindbakkerne er synlige 

 til hver Side af Overlæben som 2 eonvexe Frem- 

 spring; men deres T3'ggedele synes endnu ikke at 

 være udviklet. Derimod har enhver Kindbakke paa 

 den ydre Side et temmelig stort fodformigt Vedhæng 

 af aflang oval Form og forsynet med ialt 8 cilierede 

 Bor.ster, hvoraf 3 udgaar fra Spidsen, 3 fra en bred 

 Lap af den bagre Kand og 2 fra en noget mindre 

 Lap mellem denne og Spidsen. To Par smaa knude- 

 formige Frem.spring Timiddelbart bag Kindbakkerne 

 antyder Anlægget til de 2 Par Kjæver. Af Bran- 

 chialfødder er der Anlæg til 7 Par, snccessivt afta- 

 gende i Storrelse bagtil. De har alle Formen af 

 simple Tværvulster, uden Spor af Borster. Hale- 

 enden gaar m\ i 2 smaa tilspidsede Lappe, enhver 

 endende med en enkelt liden simpel Borste. I det indre 

 af Legemet sees tydeligt den med orangefarvet Ind- 

 hold fyldte Tarmkanal, der fortil danner to simple 

 tilrundede Blindsække. Larven bevæger sig meget 

 raskt om i Våndet ved rythmi.ske Slag af 2det Par 

 Følere, som i dette Stadium er dens eneste Loko- 

 motionsoi-ffaner. 



Det Fig. 16 af hildede Larvestadium er allerede 

 adskilligt videre udviklet. Legemet er .stærkere 

 forlænget og viser en begyndende Sondring i de 3 

 Krojjsafsnit. Hovedet er. dog endnu meget kort og 

 næsten tvært af kuttet fortil. De sammensatte Øine 

 har nil Ijegyndt at ndvikle sig som to eonvexe Frem- 

 spring ved Basis af Iste Par Følere. I deres indre 

 er der afsat en ringe Mængde rødt Pigment, og der 

 er en svag Antydning til Synselementer. De 2 Par 

 Følere og Munddelene forholder sig i alt væsentligt 

 som hos det foregaaende Stadium. Derimod er der 

 indtraadt en kjendelig Udvikling af de bag Mund- 

 delene følgende Lemmer. De i forrige Stadium Ibre- 

 kommende 7 Par simjde Tværvulster, der 1'epræsen- 

 terede AnUpgget til Braneliialfodderne, har nu Ibr- 

 detmcste sondi-et sig fra Kropssiderne og rager tyde- 

 ligt frem i Fonn af buede Pbub-r, der ei- svagt ind- 



bristles. During the movements of the oars, these 

 projections are alternately brought near to and 

 withdrawn from the oral apierture thereby assisting 

 in tlie admission of food. The inner of the two 

 rami is quite short, cylindrical, and furnished at the 

 point with 4 ciliated bristles The outer ramus, on 

 the otliei- liand, is of considerable size, about as 

 long as the scape, and tolerably thick, though ta- 

 pering towards the extremity. It is ver}' flexible, 

 and shows an indication of close articulation, the 

 margins being finely crenulated. Along its inner 

 side, there is a I'ow of 15 or Ui strong, ciliated, 

 natatory bristles, two of which issue from the very 

 point. The labrum is very large and prominent, 

 forming an oval, blunt-pointed flap extending back- 

 wards as an immediate continuation of the inferior 

 surface of the head, and (|uite covering the oral 

 aperture below. The mandililes are visible on each 

 side of the labrum in the form of 2 convex projec- 

 tions, but their masticatory part appears to be still 

 undeveloped. Each mandible has, however, on the 

 outer side, a rather large, olilong oval leg-like 

 appendage furni.shed with S ciliated bristles, 3 of 

 which issue from the ]>oint, 3 from a broad lobe of 

 the hind margin, and 2 from a somewhat smaller 

 lobe between the hind margin and the jioint. Two 

 pairs of small knoli-like projections immediately be- 

 hind the mandibles indicate the 2 inciiiient pairs of 

 maxillæ. There are indications of 6 jiairs of bran- 

 chial legs, successively decreasing in size posteri- 

 orly. They all have the form of simple transverse 

 prominences without a trace of bristles. The end 

 of the tail divides into 2 small pointed lobes, each 

 terminating in a single, small, simple bristle. "Within 

 the body may be plainly seen the intestinal canal 

 with its orange-coloured contents, forming in front 



2 sim])le, rounded cæca. The larva moves about 

 rapidly in the water with rythjnical strokes of the 

 second pair of antennæ, which, in this stage, are its 

 only organs of locomotion. 



The larval stage represented in tig. 16 is already 

 considerably unn-e developed. The body is more 

 elongated, and shows an incipient division into the 



3 sections of the liody. The head is still, however, 

 very short and almost abruptly cut off in front. 

 The compound eyes have now begun to develop in 

 the form of 2 convex projections at the base of the 

 first ]iair of anteniuc. Inside them there is a small 

 (|uantity of red pigment, and there is a faint indi- 

 cation of visual elements. The two pairs of antennæ 

 and the cral ])arts are essentiall\- in tin- same con- 

 dition as in the foregoing stadium. On the other 

 hand there is a perceptible development of the limbs 

 behind the oral |iarts. The 7 pairs of simph; trans- 

 verse jiniminences in the pre\-iiius stadium, which 

 represented the incipient branchial legs, have now 

 tbr the iiu)st piirt separated themselves ti-din the 



