4. Aischna sp. (6). 
This species is represented in our collections by a quantity 
of young nymphs, 5mm. to 24 mm. long, all taken from rushes, 
wood, ete., along the weedy margin of a lake in Yellowstone 
Park, near Gardiner River, August 30. Unlike the preceding 
species, which it closely resembles in structure, the hind angles 
of the head are rounded, and the very young nymphs are banded 
much as in Anar Junius but not on quite the same segments. 
5. Aischna californica Calv. 
A, californica, Calvert, '95. 
This is aspecies of the far West and the Pacific coast, not 
found in Illinois. The nymph is here described for the first 
time. A single one was taken from an irrigation ditch near 
Tombstone, Arizona, and bred in May, 1897, by Mr. F. C. Wil- 
lard. The exuvia and imago are now in the Cornell University 
collection. Through the kindness of Dr. P. P. Calvert, Mr. 
Needham has examined three young nymphs from the collec- 
tion of the Academy of Natural Sciences, Philadelphia, which 
appear to belong to the same species. 
The nymph measures 34 mm.; abdomen 20 mm.; hind 
femur 6 mm.; width of head, 7.5 mm., of abdomen 7.5 mm. 
The head is narrowed behind the eyes to the rounded hind 
angles, between which are two pairs of scars, the smaller pair 
on each side of the median line. The median lobe of the 
labium is not prominent; its border is without teeth, its median 
cleft closed. The lateral lobes are truncate, but their external 
angle is rounded off slightly. The supracoxal processes are 
equal and divergent at almost a right angle. 
The lateral spines on the 6th abdominal segment are slen- 
der and appressed, those on the succeeding segments increas- 
ing regularly in length. The inferior abdominal appendages 
are as long as segments 9 + 10, the laterals one half as long as 
the inferiors; the superior a little shorter than the latter, 
roundly notched as usual at the tip, and fringed with a row of 
stout blackish bristles along either side. 
