1076 Wisconsin Academy of Sciences, Arts, and Letters. 
Cyclops viridis var. parens Herrick. 
Parcus has the second segment of the fifth foot with the 
spine separated by a joint. The formula for the spines of 
the terminal segments of the exopodites of the swimming feet 
is 2, 3, 3, 3, the terminal segment of the endopodite of the 
fourth foot is armed with a seta. The outer terminal appendage 
of the furca is a short seta. 
Parcus is most common in shallow bodies of water. It does 
not appear to have a very wide distribution. 
Cyclops viridis var. americanus Marsh. 
Americanus has the furcal rami of varying length, the outer 
terminal appendage a short seta. -(Plate LXXIX, fig. 6.) 
The spine of the second segment of the fifth foot is sep¬ 
arated by a joint. The terminal segments of the exopodites 
of the swimming feet have as the formula of the spines 
3, 4, 4, 4. The terminal segment of the endopodite of the 
fourth foot has externally a seta. 
Americanus is the most abundant variety of viridis in 
American waters, being found almost universally especially 
in the smaller bodies of water. This is the form which E. B. 
Forbes calls insectus, reviving the name proposed by S. A. 
Forbes, but never so described as to make it possible to 
identify the form. It is evident that in this case americanus 
has the rights of priority, as it was possible to recognize in- 
sectus only after the publication by E. B. Forbes in 1897, 
and he recognizes the identity of the two forms. 
Discussion of viridis. 
The first to recognize clearly the identity of the forms which 
are here grouped under the common specific name of viridis 
was E. B. Forbes, and the synonomy which I have adopted 
does not differ materially from that proposed by him. I 
agree with him that all the varieties distinguished above 
merge the one into the other with no clear cut dividing line. 
This is my impression from the study of my somewhat ex¬ 
tensive collections from nearly all sections of Horth America. 
