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The faet that, in spite of this, G. W. MÜLLER chose this course is due, as is shown by
the quotation given above, partly to the incompleteness, uncertainty and undoubted
incor-reetness of se veral of the characters included in the diagnosis of the genus Cypridinodes given
by G. S. Brady, partly perhaps, above all, to the strange form Monopia flaveola described by
C. Claus, 1873.
G. W. MUller’s criticism of G. S. Brady’s diagnosis of the genus Cypridinodes is
undoubtedly quite justified. From this, however, it by no means follows that we are justified
in including the three species mentioned above in the genus Cypridina (sensu MCLLER1)!
In several respects — such as the type of the shell, the sixth and seventh limbs, the
furca and the upper lip — Monopia flaveola agrees so strikingly with the three species
mentioned that there can scarcely be any doubt of the existence of a real relationship.
Under these circumstances is it not most convenient to follow G. W. MUller’s
indication, quoted above, that, in the case of an eventual breaking-out of Cypridina
asymmetrica, C. Bairdi and C. favus we should unite these forms with Monopia flaveola
into one genus, Monopia?
I think this is true only with an important restriction. Although Monopia
flaveola — as is mentioned above — shows in several respects rather far-reaehing agreement
with the three species in question, yet it differs from them in several characters
of such importance that it seems to me quite correct to distinguish it as a representative of a
special higher classificatory unit. Thus this form is characterized by a frontal organ of a type
that is very different from other known species, by rudimentary lateral eyes (these are certainly
represented by a pair of rather short, short-stalked, somewhat T-shaped appendages, fixed
near the base of the first antenna; these appendages have been interpreted by C. CLAUS, curiously
enough and certainly incorrectly, as giils (see 1873, p. 225); and G. W. Müller (1890, p. 224)
considered them to be remains of the giils of the primitive Cypridinids!) and especially
by the slight modification of the maxilla. Contrary to the maxilla in Cypridina asymmetrica,
C. Bairdi and C. favus, but similar to the same organ in all the other representatives of the
group Cypridiniformes hitherto known, the maxilla in Monopia flaveola has immoveable
endites on the protopodite and an endopodite of fairly moderate length. On account of
this limb this species may be said in a way to occupy an intermediate position between
the three above-mentioned divergent forms and other species included in the genus Cypridina
(sensu G. W. MULLERI).
For these reasons it seems to me best to retain botli Monopia and Cypridinodes. I
con-sider them, however, as sub-genera of the same genus, Monopia. — The former sub-genus is at present
only represented by a single species, M. flaveola; in the latter are included Cypridina asymmetrica,
C. Bairdi and C. (-— Cypridinodes) favns; in addition, as is seen below, I have described
an-other species of the latter sub-genus, Monopiaf Cypridinodes) acuminata, a form that in its whole
organization shows a very striking resemblance to the representative of this sub-genus described by
G. W. Müller. — With regard to the distinguishing characters of these two sub-genera I merely
refer here to C. Claus, 1873 and to the diagnosis of the sub-genus Cypridinodes that is given
later on in this work.
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