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thoroughgoing study of tlie organs of copulation in the Cytheridae, one of the most difficult
problems presented by tbis group of animais.
For more detailed information with regard to the progress of the study of the O s t r
a-c o d s’ special classification, morphologv, etc. 1 mav refer the reader to the historical résumés
to be found in the succeeding part of this work in connection with the discussion of the various
units of the system.
During this period the fundamental features of the natural system of the Ostracod s Xatural system.
underwent the folio wing development:
W. Baird was the first to divide this group into families. In his above-mentioned work
1850a, ,,N atural H i s t o r y o f t h e B r i t i s h E ntomostrac a“ a rather
eminent work for its time, this author divides the Ostracod group into three families*:
Family I. Cypridae with the genera Cypris and Candona.
,, TI. Cytheridae ,, ,, ,, Cythere and Cythereis.
,, III. Cypridinadae „ ,, genus Cypridina.
The families are classified bv this author directly into genera.
J. D. Dana makes a further very important advance. In his monumental work on the
Crustacea brought home by the ,,U n i t e d States Exploring Expedition“ of
1852, he divides the Ostracods, called Cypridacea or Cyproidea, into two families, both
composed of two sub-families:
Family I. Cypridae, comprising the sub-families Cyprinae and Cytherinae.
,, IT. Halocypridae, ,, ., Cypridininae and Halocyprinae.
The last-named sub-family comprises the two mteresting genera discovered by this
author, Halocypris and Conchoecia. The sub-families are divided in this work directly into
genera and species. This classification mav be said to form the basis of the present system of
the Ostracods.
The classification employed by O. 0. Sars in his work on the 0 s t r a c o d s of Norway,
1865, certainly follows that worked out by .1. D. Dana, but is, however, noteworthy partly
on account of the far-reaching extention of the new groups by the establishment of a rather
large number of new genera, partly by the founding of some new main groups, based on forms
that were completely or almost completely unknown to former authors, partly too because
in this work the names nowadays adopted for the large main groups were used for the first time.
G. O. Sars divides the Ostracods into four sections, comprising altogether six families:
Sectio 1. Podocopa comprising the. families Cypridae and Cytheridae
II. Myodocopa, ,, ,, ,, Cypridinadae and Cnnrhoeriadae
„ III. Cladocopa, ,, ., l’amilv Polycopidae
,, IV. Platycopa, ,, „ .. Cythereii idae.
* lu a scheine on p. 14 of the same work, in which W. lUinn savs that ho wishos to ..nive a connected view
of the arrangement of the Hritish Entomostraca which I propose to adopt“ this author, curiously enough, makes tho
Ostracods comprise only one familv, named Cyprulittaf\ inchiding all lim fi\ ■ ahov-mcnlioned généra. 1 his
last-mentioned division is also found in this author s work ot I8 >nr.
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