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and comprehensive arguments than those put forward by G. W. MÜLLER are an absolute necessity.
Above all the question as to whether the nervous system may, in spite of its changed condition,
possibly afford some information on this subject must be investigated.
The assumption that the Protostracods were characterized by a heart, lateral e7es Heart and eyes.
and an unpaired median eye with three parts seems to me very probable. It is now generally
considered, as we know, that these organs belonged to the Protostraca. Other writers previous
to G. W. Müller expressed similar views to his. As early as 1859 E. GRUBE pointed out, p. 326,
that the genera Gypridina and Aster op e resembled the Cladocera by their lateral eyes, among
other things. C. Claus, in his work of 1865, p. 147, stated that by having a heart and by the
development of the organs of sight Gypridina resembled the D a plin i ds; from his later works
it is also clear that he considered these characters as being primitive for the Ostracods.
Finally it may be pointed out that F. MÜLLER, 1870, p. 273, assumed that the
Protostracods had a heart. In this connection it may also be pointed out that L. LüDERS, 1909,
pp. 117—118, assumes that the genus Gigantocypris, on account of its well developed system of
blood-vessels and its development of blood-corpuscles, is to be considered as more primitive in
this respect than other known Ostracods.
With regard to the assumption that the Protostracods had alimentary organs Alimeiuary organs.
of about the same simple type as those of the recent Cypri dinids it seems to me that
no serious objection can be raised against it. We may note, however, that W. GlESBRECHT,
1913, p. 228, states that Protostraca presumably had metamere coeca on the middle part of
the intestines „jedenfalls gab es coeca an seinem Vorder- und Hinterende“. We find hepatic
coeca among the Cypridinids (Asterope) and Haloeyprids as well as among
Cyprids, Nesideids and Cytherids.
The number of the limbs: — The assumption that the Protostracods Number af the limbs
werewithout the limb corresponding to the second maxilla of other Crustacea is connected with the
assumption made by this writer, and some others. fchat the recent Ostracods never have this
appendage. With regard to this question I only refer here to what has been shown in connection
with this subject on p. 20 of this treatise; see also the brush-shaped organ and the penis.
The question of the nature of the so-called brush-shaped organ is very difficult Brush-shaped organ
to decide. It is perhaps a limb. But in this case which one?
In the Nesideids and the Cytherids this organ is always found in the males,
never in the females; in these groups we find it most frequently in the neighbourhood of the
fifth limb, sometimes a little in front of and sometimes a little behind it, but it is rarely found
so far back as between the sixth limbs. Among the Cyprids it has so far been observed
only in one genus, Macrocypris. It has also been found in CythereUa. In the two latter genera
this organ is also confined to the males; it is not situated, however, at the same place as in
Nesi-deidae and Gytheridae, but near or somewhat behind the seventh limb. Among the
Cypridinids this organ has been observed by G. W. MÜLLER behind the seventh limb in the
female of Cypridina squamosa G. W. MÜLLER. In all other species of this group, as in all the
Haloeyprids and P o 1 y c o p i d s in which this organ was sought for, even in the
forms investigated by me, it was not found.
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