ENTOMOSTRACA OF MINNESOTA. 249 
A. pygmeea is Alonella. 
A. parvula Kurz is A. guttata. 
A. rectangularis is A. pulchra. 
A. rostrata is Alonella. 
A. reticulata Bd. is Graptoleberis. 
A, striata is Alonella. 
A, suleata is A. quadrangularis. 
A, spinifera Schoedler is the young of some species. 
A. socors O. F. Muller is uncertain. 
A, tuberculata Kurz is A. guttata. 
A, tuberculata Hudendorff is A. coronata. 
A. transversa is Alonella pygmea. 
A. testudinaria is Graptoleberis. 
A. verrucosa Lutz is A. guttata. 
Section B, Alonella Sars. 
In this group are included small species with a combination of 
characters, forming the link between dA/ona and Pleuroxus. An obvious 
character is the fact that the shell is usually partly marked by oblique 
strie, which run in two directions: first, a set extending forward and 
upward from the lower posterior angle of the valves; second, a set 
springing from the anterior and lower angle, running across the 
others. At the central part where these two series intersect, they 
each become zigzag; the result is a series of hexagonal markings, 
which may extend to the middle of the lower margin. 
The beak is short and the fornices broad; the shell is more or less 
rectangular, but somewhat elevated in the middle above. 
There are usually but seven sete on the antenne, or the eighth is 
a minute hair; on the ramus having the lateral setz one of the terminal 
sete is frequently reduced. In many cases the whole shell is marked 
by minute strive in addition to the proper markings, but this is also 
found in some species of the true Pleuroxus. Kurz gives, as a character 
of Alonella, the presence of but a single basal spine to the claw of the 
post-abdomen; but P. E. Mueller figures two spines on the claws of one 
of his species (4. exigua), and Schoedler figures eight setze on the an- 
tenna of A. ercisa. American specimens of A. excisa and of A. pygincea 
both certainly have a very minute eighth seta. There remains, there- 
fore, positively no point which can be relied upon to distinguish 
these little Zynceids from Pleuroxus or Alona. Perhaps, however, these 
Species, aS a group, may be recognized by what has already been said. 
Three species are found in Minnesota. 
