474 Wisconsin Academy of Sciences, Arts, and Letters. 
querquensis Herrick and D. albuquerquensis Schacht are not 
identical. The figure of the male fifth foot given by Schacht 
is very different from that figured by Herrick, and I think it 
probable that it belongs to D. saltillinus Brewer. The figure 
of the female fifth foot is of neither D. saltillinus nor D. albu¬ 
querquensis , as both species have a short endopodite. Schacht 
states that his D. albuquerquensis was found in connection with 
D. mississippiensis, and his figure would correspond very well 
to the fifth foot of the female of that species. It seems proba¬ 
ble, then, that Schacht’s description is a composite of D. sal¬ 
tillinus and D. mississippiensis, and that he had no specimens 
of D. albuquerquensis. 
DIAPTOMUS ASYMMETRICUS Sp. nOV. 
Plate XXV, fig. 6. Plate XXVI, figs. 1, 3, 4. 
A small species. The first cephalothoracic segment is long¬ 
er than the three following. The second, third and fourth 
segments are about equal in length, the fifth somewhat longer. 
The lateral expansions of the last thoracic segment are armed 
on each side with an acute spine. 
The first segment of the female abdomen is much longer 
than the rest of the abdomen. It is expanded laterally at a 
little less than one-third its length; the dilatations are armed 
with acute spines which are slightly recurved. The dilatation 
on the front of the segment is very pronounced. At about 
two-thirds the length of the segment, and on the right side, is 
a blunt, rounded projection, which is much more prominent 
than the lateral dilatation. The second segment is short. The 
third segment is fully four times as long as the second, and is 
about equal in length to the furca. The distal end of the fur- 
cal ramus is nearly twice as wide as the proximal; the furcae 
are ciliate on the inner margin. 
The antennae are 25-segmented, and in the female extend 
beyond the tip of the furcae. The right antenna of the male 
is much swollen anterior to the geniculating joint. The an- 
