408 Wisconsin Academy of Sciences, Arts, and Letters . 
metrical, its distal end being expanded to the 
right, . Trybomi 
The endopodites are two-segmented, 
Terminal spines of endopiodite fully as long as 
the endopodite, a large species, . .stagnalis 
Terminal spines of endopodite short, a moder¬ 
ate sized species, . Eiseni 
The first antennae equal or exceed the length of the 
whole body including the furca, 
The endopodite is rudimentary, . niinutus 
The endopodite equals in length about one-half the 
first segment of the exopodite, 
Fifth cephalothoracic segment with dorsal pro¬ 
cess, endopodite one-segmented, . saltillinus 
Fifth cephalothoracic segment with dorsal pro¬ 
cess, endopodite commonly two-segmented, . .aVbuquerquensis 
The endopodite exceeds in length one-half the first 
segment of the exopodite, 
The fifth cephalothoracic segment is armed with 
two dorsal processes, . dorsalis 
The first segment of the abdomen has a prom¬ 
inent swelling on the right side. asymmetricus 
The endopodite equals or exceeds in length the first 
segment of the exopodite, 
There is a digitiform process on the right pos¬ 
terior border of the first abdominal segment. 
This process is variable in length, typically, 
in signicauda, extending far beyond the sec¬ 
ond segment, signicauda, nudus, washingtonensis, Judayi 
(These species can be satisfactorily separated 
only by the characteristics of the male. Gen¬ 
erally the abdominal process is much more pro¬ 
nounced in signicauda. The lateral projec¬ 
tions of the abdomen are strongest in Judayi, 
less pronounced in nudus and about equally 
prominent in washing tonensis and signicauda). 
The first abdominal segment bears no process on its 
right hand posterior margin, 
The lateral spines of the abdomen are either ab¬ 
sent or very minute, 
The exopodite is distinctly three-segmented, 
Antennae equal to cephalothorax, a very 
large species, .... shoshone 
Antennae reach to furca, . Wardi 
The exopodite is two-segmented, the abdomen 
elongated, 
The abdomen is very much elongated, the 
lateral swelling of the first segment very 
slight, . tenuicaudatus 
