54 



fjernet og nærmet til Mandaabningen og bidrager 

 derved til Fødens Optagelse. Af de 2 Grene er den 

 indre ganske kort, cylindrisk og forsynet paa Spid- 

 sen med 4 cilierede Børster. Den ydre Gren er der- 

 imod af betydelig Størrelse, omtrent saa lang som 

 Skaftet og temmelig tyk, dog gradvis afsmalnende 

 mod Enden. Den er meget bøielig og viser en An- 

 tydning til en tæt Leddeling, idet Kanterne er fint 

 crennlerede. Langs ad dens indre Side iindes en 

 Rad af 15 — 16 stærke, cilierede Svømmebørster, 

 hvoraf 2 udgaar fra selve Spidsen. — Overlæben er 

 meget stor og fremspringende, dannende en oval, i 

 en stump Spids endende og i Flugt med Hovedets 

 lindre Flade gaaende Klap, der ganske dækker 

 Mundaabningen nedad. — Kindbakkerne er synlige 

 til hver Side af Overlæben som 2 convexe Frem- 

 sjDring; men deres Tyggedele synes endnu ikke at 

 være ndviklet. Derimod bar enhver Kindbakke paa 

 den ydre Side et temmelig stort fodformigt Vedhæng 

 af aflang oval Form og forsynet med ialt 8 cilierede 

 Børster, hvoraf 3 ixdgaar fra Spidsen, 3 fra en bred 

 Lap af den bagre Rand og 2 fra en noget mindre 

 Lap mellem denne og Spidsen. To Par smaa knude- 

 formige Fremspring nmiddelbax't bag Kindbakkerne 

 antyder Anlægget til de 2 Par Kjæver. Af Bran- 

 chialfødder er der Anlæg til 7 Par, successivt afta- 

 gende i Størrelse bagtil. De har alle Formen af 

 simple Tværvulster, uden Spor af Børster. Hale- 

 enden gaar ud 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 rythmiske Slag af 2det Par 

 Følere, som i dette Stadium er dens eneste Loko- 

 motionsox'ganer. 



Det Fig. 16 afbildede Larvestadium er allerede 

 adskilligt videre udviklet. Legemet er stærkere 

 forlænget og viser en begyndende Sondring i de 3 

 Kropsafsnit. Hovedet er dog endnu meget kort og 

 næsten tvært af kuttet fortil. De sammensatte Øine 

 har nu begyndt at udvikle sig som to convexe Frem- 

 spring ved Basis af Iste Par Følere. I deres indre 

 er der afsat en ringe Mængde rodt Pigment, og der 

 er en svag Antydning til Synselenienter. De 2 Par 

 Følere og Munddelene forholder sig i alt væsentligt 

 som hos det foregaaende Stadium. Derimod er der 

 indtraadt en kj endelig Udvikling af de bag Mund- 

 delene følgende Lemmer. De i forrige Stadium lore- 

 kommende 7 Par simple Tværvulster, der repræsen- 

 terede Anlægget til Branchialfodderne, har nu for- 

 detmeste sondret sig fra Kropssiderne og rager tyde- 

 ligt frem i Form af buede Plader, der er svagt ind- 



bristles. During the movements of the oars, these 

 projections are alternately brought near to and 

 withdrawn from the oral apertixre thereby assisting 

 in the admission of food. The inner of the two 

 rami is quite short, cylindrical, and furnished at the 

 jjoint with 4 ciliated liristles. The outer ramus, on 

 the other hand, is of considerable size, about as 

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

 pering towards the extremity. It is very flexible, 

 and shows an indication of close articixlation, the 

 margins being finely crenulated. Along its inner 

 side, there is a row of 15 or 16 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 quite covering the oral 

 aperture below. The mandibles are visible on each 

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

 tions, but their masticatory part appears to be still 

 ixndeveloped. Each mandible has, however, on the 

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

 appendage furnished with 8 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 point. Two 

 pairs of small knol>like projections immediately be- 

 hind the mandibles indicate the 2 incipient pairs of 

 maxillæ. There are indications of 6 pairs 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 simple, rounded cæca. The larva moves about 

 rapidly in the water with x-ythmical strokes of the 

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

 only organs of locomotion. 



The larval stage represented in fig, 16 is already 

 considerably more developed. The body is more 

 elongated, and .shows an incipient division into the 



3 sections of the body. 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 jjair of antennæ. Inside them there is a small 

 quantity of red pigment, and there is a faint indi- 

 cation of visual elements. The two pairs of antennæ 

 and the oral parts are essentially in the same con- 

 dition as in the foregoing stadium. On the other 

 hand there is a perceptible development of the limbs 

 behind the oral parts. The 7 pairs of simple trans- 

 verse prominences in the previous stadium, which 

 represented the incipient branchial legs, have now 

 for the most ]3art separated themselves from the 



