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 receptaculum seminis is shown in PI. 
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 ( l'6th 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- 
five degrees with the long axis of the segment, instead of at 
right angles. In edax the distal segment is broader. 
6th. Other differences which can only be recognized by a 
