commoner of the two species found in such situations, the other being as 
yet undescribed.* 
These eggs are attached as closely as they can be placed, by the end 
opposite the micropyle, and do not seem especially to inconvenience their 
bearers. 
The point of attachment preferred is the margin of the abdomen, out of 
the way of the legs ; but the eggs are gradually extended along the sides of 
the cephalo- thorax until sometimes the body is almost entirely covered. A 
careful search of the weeds and other submerged objects in the ponds dis- 
covered no other place of deposit of these eggs. As these ponds usually go 
dry during the summer, it seems not unlikely that the Corixa may attach its 
eggs to the crawfish in order that the latter may, in such an event, carry 
them to other waters. It is not to be supposed, however, that the Co- 
rixa is entirely dependent on the crawfish for the preservation of its progeny , 
for the parent can fly, and is occasionally taken on the wing ; nevertheless, 
this curious expedient must prevent a great waste of eggs, and so operate to 
the advantage of the species. But the subject requires further study. 
C. obesus, Hagen. Very common. The largest in the state. 
C. gracilis, Bundy.* “Rostrum short, wide, depressed, concave above,, 
acumen short ; cephalo-thorax compressed, areola none, the pleura meeting 
on median line of dorsum, posterior spatium much wider than anterior : 
chelae long : inner margin tuberculate-serrate, fingers slender toward apex, 
outer one with strong tubercle on inner margin near base, movable finger 
with strong tubercle near middle of inner margin ; carpus long, strongly 
toothed on inner, and lower front margins ; third maxillipedes hairy on in- 
ner sides ; third joint of third thoracic legs hooked ; first abdominal legs of 
maie truncate, with several small apical teeth, of which the inner one is 
much longest, slender and pointed outward, base of these legs inserted in 
deep sinuses in the strongly developed ventral part of first abdominal seg- 
ment. Ventral ring of female movable longitudinal fissure widest be- 
hind.” ( W. T. Bundy.') Very common along water courses in early spring. 
It was first detected by Prof. Bundy, in the museum collections, in the au- 
tumn of 1875, has since been taken in great numbers at Normal, and has 
been received by Prof. Bundy, from Racine, Wis. 
Palaemon ohionis , Smith. Abundant at Cairo, where it is frequently 
eaten. Smaller specimens were taken in the Mississippi near Grand Tower, 
in Jackson county, and it is reported by boatmen to occur from St. Louis 
to New Orleans, growing larger towards the south. It has not yet been 
found in the Illinois River. 
Palaemonetes exilipes, Stimp. Very common in the Illinois River, 
where it seems to be the only shrimp. Taken in large numbers at Pekin. 
Hyalella dentata , Smith. Occurs in myriads in the swamps of the Cal- 
umet river, at South Chicago, and sparingly in Rock river, at Oregon, 
Ogle county. Not seen further south. 
*Uhler. 
*The descriptions quoted have been kindly furnished me by the discoverer of the 
species. 
