ENTOMOSTRACA OF MINNESOTA. 237 
*Dunhevedia setiger Birge. 
PEATE LXIV, Fie. 13. 
Length 0.4 mm. to 0.6 mm. Minnesota specimens measured 0.5 
mm. This species is but rarely encountered, and is so peculiar as to 
be easily recognized when seen. Alona intermedia has a post-abdomen 
with clusters of bristles, but in Dunhevidia the post-abdomen is more 
asin species of Graptoleberis than any other genus. The markings 
upon the shell are very indistinct. Birge says that the male is simi- 
lar in form to the female. The first foot has a stout hook. Theclaws 
are smooth in both sexes. This species has been found by Daday in 
Hungary. 
GENUS LYNCEUS O. F. Miller. 
The perplexing inter-relations between the three genera Alona, 
Alonella and Pleuroxus give rise to the utmost confusion. No two 
authors are agreed as to their respective limits, and the points given 
by Kurz, who has carefully gone over the ground, are obviously in- 
sufficient. Although there may be practical benefits to be derived 
from the continuance of the nomenclature in use for groups which 
in the general view can be distinguished, the value from a theoretical 
standpoint is reduced to a minimum. 
The genus Camptocercus (including here Acroperus, which differs 
solely in the form of the abdomen, as a sub-genus) passes through 
Alonopsis into the group represented by Alona. Leydigia, although 
very near such forms as Alona quadrangularis, may be conveniently 
distinguished as a transition to species like Jlyocryptus. 
Phrixura, Graptoleberis and Dunhevidia, each containing few species 
which can be readily recognized, fill a place in the system; but it is 
practically impossible to distinguish Alona from Pleuroxus without in- 
stituting the very indefinite genus Alonella to contain a variety of 
small intermediate forms. Percantha, Rhypophilus, Harporhynchus and 
Pleuroxus seem to be pretty generally regarded as constituting a single 
group which may be recognized by the long rostrum, high shell and 
greater development of the antenna bristles. Alona, on the other 
hand, with its broader fornices, shorter beak, fairly developed an- 
tenn, and more rectangular shell, is, perhaps, the pivotal point of 
the group. According to this view, then, the old name Lynceus is re- 
vived for the aggregate; and the other names are retained, in part, 
as titles of largely conventional groups or sub genera, thus: 
