418 Wisconsin Academy of Sciences, Arts, and Letters. 
speaks of it as in the entire Mississippi valley, but without 
specifying definite locations. 
Schacht (’97, p. 146) says it is extremely abundant near 
Havana, Ill. I have found it in only one locality in Wiscon¬ 
sin,—Heart lake near Marquette. I have also found it in 
collections from Elk lake, Clay county, Iowa. Erom the south¬ 
ern states I have found it from Missouri, Tennessee, Arkansas, 
Louisiana and Texas. It occurs, too, in Lake Minnequa in 
Pueblo, Colorado, and in eastern Nebraska, and the presump¬ 
tion is that it occurs at intermediate points between the Eocky 
mountain region and the observed stations farther east. So 
it would appear that it is not only found throughout the Mis¬ 
sissippi valley, but that it is pretty well confined to that valley, 
and much more abundant in the middle and southern part of 
the region. 
DIAPTOMUS EBANCISCANUS Lilljeborg. 
Plate XXVI, figs. 7, 11. Plate XXVII, figs. 1, 2. 
1889. Diaptomus franciscanus HeGuerne and Eichard, p. 48; 
pi. I, figs. 12, 13, 34; pi. Ill, fig. 23. 
1895. Diaptomus franciscanus Herrick and Turner, p. 58; pi. 
VIII, figs. 12 and 16. 
1897. Diaptomus franciscanus Schacht, p. 160; pi. XXX, figs. 
1-4. 
Eather large. Cephalothorax widest at the middle, the last 
two segments confluent above. The lateral lobes, seen from 
above, are short and obtuse posteriorly, and armed on each 
side with two small spines. The first segment of the abdomen 
is about equal in length to the rest of the abdomen, is moder¬ 
ately dilated in front, rounded at the sides, bears two small 
lateral spines, but lacks lateral processes. The indications of 
a joint—an imperfect suture—remain long after maturity in 
the posterior part of this segment. The second abdominal seg¬ 
ment is much shorter than the third, its test more delicate and 
easily pushed together. The furcal rami are short, their length 
