rundet Form, med den ovre Kant, hvor Valvlerne 
stoder sammen, neesten ret og endende saavel fortil 
som bagtil med et tydeligt fremspringende Hjorne. 
Ovenfra seet (se Fig. 8) viser den sig temmelig 
buget, idet Breden nesten er lig Hoiden. Til hver 
Side sees Skalkjertelen med den umiddelbart foran 
samme liggende Muskelarea med stor Tydelighed, 
og paa Grund af Skallens store Gjennemsigtighed 
treeder ogsaa den af samme bedekkede Del af Lege- 
met klart og tydeligt frem. Man kan nu paa Lege- 
met adskille alle de Afsnit, som ovenfor er beskrevet 
hos det voxne Dyr. Dog er Nakkesegmentet endnu 
temmelig kort, og Truncus kun lidet lengere end 
det forreste Afsnit af Legemet. Hovedet har en 
fra samme hos det voxne Dyr temmelig afvigende 
Form. Dets ovre Flade er noget uregelmessigt 
hvelvet og endnu uden Spor af det characteristiske 
stilkede Fastheftningsorgan, som forst senere dan- 
nes ved en gradvis Afsnoring af en Del af Hovedets 
Dorsalparti. Pandedelen er endnu kun lidet frem- 
springende, og mellem den og det stumpt tilrundede 
Rostrum er der neppe engang den svageste Indbugt- 
ning at se. Af Hovedets Vedheng er iste Par Fo- 
lere lidt mere forlengede end hos Larverne, men 
endnu forholdsvis smaa og uden laterale Lappe. 
2det Par Folere, eller Aarerne, har, som ovenfor 
anfort, tabt baade den bagudbgiede Borste ved Enden 
af Skaftet og den tvedelte basale Fortsats. For- 
ovrigt stemmer de, saavel hvad Skaftets som Gre- 
nenes Bygning angaar, temmelig ner overens med 
samme hos Larverne, alene med den Forskjel, at 
der i Yderkanten af den ovre Gren har udviklet sig 
en kort Pig, hvoraf intet Spor var at se hos hine. 
Overleben er nu betydelig reduceret i Storrelse og 
har antaget det for det voxne Dyr characteristiske 
Udseende, idet den lange, dolkformige Endedel er 
svundet ind til en forholdsvis liden tentakelformig 
Fortsats. Paa Kindbakkerne er der endnu igjen et 
Rudiment af Mandibularfodderne i Form af et til 
deres Yderside festet ubetydeligt koniskt Appendix 
uden Spor af Leddeling eller Borstebesetning. Bag 
Kindbakkerne sees de 2 Par Kjever, som nu, lige- 
som Kindbakkerne, er i fuld Virksomhed med at 
bearbeide den optagne Nering. De hos Larven an- 
lagte 6 Par Branchialfodder er nu functionsmessigt 
udviklede, udforende sine characteristiske svingende 
Bevegelser for Respirationens og Neringsoptagel- 
sens Formaal, og bag dem er der endnu Anleg 
til 3 eller 4 Par nye Fodder. -Haledelen er endnu 
kun svagt omboiet og Haleklorne ufuldstendigt son- 
drede fra Haleenden. De har hver ner Basis en 
enkelt kort Sidetand, og umiddelbart ovenfor dem 
udgaar fra Halens Dorsalside 2 meget smaa jevn- 
sides stillede Fremspring, som forestiller det forste 
Anleg til de tandede Haleplader. Ovenfor Hale- 
borsterne har der endvidere udviklet sig et enkelt 
Par af de hos det voxne Dyr her forekommende 
107 
_ to be seen. 
valves meet, almost straight, and ending both in 
front and behind in a distinctly projecting corners 
Seen from above (see fig. 8), it appears rather 
bulging, its breadth being almost equal to its 
height. On each side is seen the shell-gland very 
distinctly, with the muscular area lying immediately 
in front of it; and on account of the great trans- 
parency of the shell, that part of the body which 
it covers is seen very clearly and distinctly. All 
the sections of the body described above in the 
adult animal, can now be distinguished. The cervi- 
cal segment, however, is still rather short, and the 
trunk only a little longer than the foremost section 
of the body. The head has a rather different shape 
to that in the adult animal. Its upper surface is 
somewhat irregularly arched, and still without a 
trace of the characteristic stalked organ of attach- 
ment, which is formed, but not until later, by a 
gradual constriction of a part of the dorsal region 
of the head. The frontal region still projects only 
slightly, and between it and the bluntly rounded 
rostrum, there is scarcely even the slightest hollow 
Among the appendages of the head, 
the first pair of antenne is a little more elongated 
than in the. larva, but still comparatively small 
and without lateral lobes. The 2nd pair of antenne, 
or the oars, have, as stated above, lost both the 
backward-curved bristle at the end of the scape and 
the bifid basal projection. In other respects they 
agree very closely, as regards the structure of both 
the scape and the rami, with those limbs in the 
larva, with the one difference that in the outer 
margin of the upper ramus a short spike has deve- 
loped, of which there was no trace in the larva. 
The labrum is now considerably reduced in size, 
and has assumed the appearance characteristic of 
the adult animal, the long, ensiform terminal part 
having shrunk into a comparatively small, tenta- 
cular projection. There is still a rudiment of the 
mandibular legs left on the mandibles in the form 
of an indistinctly conical appendage, — without a 
trace of articulation or bristles, — attached to their 
outer side. Behind the mandibles are seen the 2 
pairs of maxille, which now, like the mandibles, 
are in full activity, manipulating the food admitted. 
The 6 pairs of branchial legs commenced in the 
larval stage are now able to perform their function, 
executing their characteristic swinging movements 
for the purpose of respiration and the admission of 
food; and there are the rudiments of 3 or 4 pairs 
of new legs. The caudal part is still only slightly 
bent down, and the caudal claws imperfectly marked 
off from the end of the tail. They each have near 
the base a single, short, lateral tooth, and imme- 
diately above them, there issue from the dorsal 
side of the tail 2 very small juxtaposed projections, 
_ representing the earliest rudiment of the dentated 
