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Skinner, Ernest B. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume XIV, Part I (1902)

Lehmann, Harriet
Variations in form and size of Cyclops brevispinosus Herrick and Cyclops americanus marsh,   pp. [279]-Plate XXXIII ff.

Page [279]

                 AMERICANUS MARSH.
                 BY HARRIET LEHMANN.
  This investigation was undertaken under the direction of
Professor C. Dwight Marsh of Ripon College, to determine
the extent of variation. in C. brevispinosus Herrick and C. amer-
icanius Marsh, particularly with reference to the question of
specific distinction between these forms in the form and meas-
urements of the, furca., and the outer terminal spine of the
furca, and in the armature of the terminal joint of the inner
ramus of the fourth swimming foot.
  The results obtained cannot, however, be considered con-
clusive, since the number of specimens examined was insuffi-
cie~nt to permit- exact- conclusions. The variations were also
found to be so wide in a small number of specimens that even
greater variation might be possible in a large number.
  Different investigators do not agree as to the characters of the
genus Cyclops important for specific distinctiom Brady, '78,
gives, "the characters of the first antennae and fifth pair of feet
As offering subsidiary characters, the spinous armature of the
swimming feet, together with the tail segments and setae, are
also. important." Schmeil, '92, says, "Die sichersten und
einfachsten Erkennungsmerkmale sind das rudimentiire Fiis-
schen mnd der Bau des Receptaculum, seminis. *  *    *Die
Anzahl der Borsten und Dornen ist fur die Individuen einer
Art durchaus nicht konstant, so das allien heiraufgegriindete
Arten hinfiallig werden.  Hiermit soll natiirlich nicht ausge-
sprochen sein dass die Beriicksichtigung der Bewehrung der
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