ENTOMOSTRACA OF MINNESOTA. 249 



A. pygmcea is Alonella. 



A. panmlii Kurz is A. r/uttafa. 



A. reetangularis is A. pulchra. 



A. rostrata is Alonella. 



A. reticulata Bd. is Graptoleheris. 



A. striata is Alonella. 



A. sulcata is A. quadrangularis. 



A. spinifera Schoedler is the young of some species. 



A. socors O. F. Miiller is uncertain. 



^4. tuberculata Kurz is A. guttata. 



A. tuberculata Hudendorff is A. coronata. 



A. transversa is Alonella pygmea. 



A. testudinaria is Graptoleheris. 



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 Alona and Pleuroxus. An obvious 

 character is the fact that the shell is usually partly marked by oblique 

 striee, 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 foruices broad; the shell is more or less 

 rectangular, but somewhat elevated in the middle above. 



There are usually but seven set?e on the antenme, or the eighth is 

 a minute hair; on the ramus having the lateral setse one of the terminal 

 setse is frequently reduced. In many cases the whole shell is marked 

 by minute strife 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 {A. exigua), and Schoedler figures eight setre on the an- 

 tenna of A. excisa. American specimens of A. excisa and of A. pygmcea 

 both certainly have a very minute eighth seta. There remains, there- 

 fore, positively no point which can be relied upon to distinguish 

 these little Lynceids 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. 



