1084 Wisconsin Academy of Sciences, Arts, and Letters. 



on its distal end, and an almost equally long one on its inner 

 side. This appendage of the inner side is spoken of by Schmeil 

 as a spine, but in most of our specimens it would more properly 

 be called a seta. There is a good deal of variability in the 

 form and proportions of the fifth feet as shown in the figures 

 of the plate. 



The egg sacs are carried at a marked angle from the abdo- 

 men. 



The form of the reoeptaculum seminis is shown in PL 

 LXXIV, fig. 7. Average length of females is about 1.14: mm. 



This is a truly cosmopolitan species, being found in nearly 

 all parts of the world. In India it is reported as found not 

 only in fresh water but in brackish ponds. (Annandale 1907.) 



The synonomy of this species prior to 1891 has been dis- 

 cussed by Schmeil and there is no reason to dissent from his 

 conclusions. 



As pointed out by me in an earlier publication (Marsh '92) 

 it appeared from Forbes' s original description of edax, that 

 the only reason for separating it from Leuckarti was the ab- 

 sence of hyaline membranes on the 16th and 17th antennal 

 segments. E. B. Forbes (Forbes '97) redescribes the species. 

 He states that the hyaline membranes are present on the 16th 

 and 17th segments. 



He makes the following points of difference between edax 

 and Leuckarti: 



1st. The hyaline membrane of edax has several deep inden- 

 tations, Leuckarti but one. 



2nd. In edax the 16th and 17th antennal segments are equal, 

 in Leuckarti the ,16th is a fourth longer. 



3rd. The crenulations of the second segment of the outer 

 maxillipedes are less marked. 



4th. The abdominal stylets are more divergent in edax. 



5th. In edax the surfaces of attachment of the setae of the 

 terminal segment are parallel, in Leuckarti the surface of at- 

 tachment of the proximal seta is at an angle of about forty- 

 tive degrees with the long axis of the segment, instead of at 

 Tight angles. In edax the distal segment is broader. 



6th. Other differences which can only be recognized by a 



