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as a very short, upward pointing peg, without bristles. The s i x t h 1 i m b has a more markedly
larval type tlian in the preceding stage; it is represented only by a rounded, unjointed or almost
unjointed, weakly two-lobed little plate, of about the same type as is shown in fig. 22, pl. 34,
G. W. MÜLLER, 1894; the proximal joint usually has only one bristle; the distal one has no
bristles, only numerous stift’ hairs. Each f u r c a 1 lamella has six or seven claws, of
which the two distal ones dominate rather decidedly over the others; cf. fig. 13 of this
species in the special part of this work. The lateral eye s, the median eye and the
rod-shaped organ are rather well developed, the median e y e, however, is only
rather slightly pigmented.
Stage V: — Shell: Average length, 1 mm.; length : height = 1,4 : 1. Mdiile the
preceding larval stages were characterized by a shell whose length was somewhat greater in
proportion to its height than in the mature female, this stage, like the following, shows a shell
in which the proportion between length and height is about the same as in the mature female.
The s e v e n t h 1 i m b is quite absent. The s i x t h 1 i m b is developed only as a small
undifferentiated, downward pointing peg with stift hairs. The o t h e r 1 i m b s have about
the definitive fundamental type, but have a somewhat more larval appearance than in the
preceding stage — especially in the case of the bristles. Each f u r c a 1 lamella has only
five or six claws, the two distal of which dominate over the others even more strongly than in
the preceding stage. The lateral eyes are large and fairly well developed, the median
eye and the rod-shaped organ are developed but have a decidedly larval appearance ;
the médian eye has scarcely any pigment.
Stage VI: — This is the youngest free-living larval stage that I found. Shell:
Average length, 0,9 mm.; length : height = about 1,4 : 1. Even in this stage the shell has about
the sanie type, when looked at from the side, as in the mature stage. It agréés fairly closely
with the preceding stage; the s i x t h 1 i m b is almost as much developed here as in this stage.
The next stage that I found had not yet left the brood chamber. Its length was only
0,6—0,7 mm. The lateral eyes were large and well pigmented but had no ommatids
developed. The limbs were scarcely developed. Possibly it ought really to be termed an embryo.
Although the length classes that were observed were thus in a number of cases rather
closely related to each other morphologically, there can be no doubt that each of them
represents a moult.
G. W. MÜLLER in his Ostracod monograph, 1894, gives a short description of the three
youngest larval stages of Cypridina mediterranea O. COSTA. According to this author the larva
of this species leaves the brood chamber as soon as it has been hatched from the egg. The
youngest free-living larval stage has about the same shape of shell as the mature specimens, only
„etwas kürzer und höher“. The five anterior limbs have about the definitive type, but the
fifth limb „mit wesentlich geringerer Anzahl von Borsten und zahnartigen Gebilden“. The
sixth limb is already formed, but is very simple; it has a „bereits an die definitive Gestalt
erinnernde Form“,* and has no bristles at all. The furca has five claws, the two distal of which
dominate strongly over the others.
* Pl. 34, Hg. 21 shows a type very like that described by me above for Stage V.
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