80 THOMAS SAY FOUNDATION 
Abdomen depressed, quite uniformly yellowish brown; cerci 
long and slender, and composed of about forty segments, each 
segment tipped with a whorl of spines or hairs. 
The gills of this species are longer in proportion to the size of 
the body and more copious than in any other known nymphs. 
They are located as follows; two pairs at the outer base of the 
front legs; one pair, each consisting of two main trunks, on the 
lateral margin of the conjunctivae between the pro- and meso- 
thorax; two pairs at the outer base of the lateral margin of the 
conjunectivae between the meso- and metathoracic legs; one pair, 
each with three main trunks, at the postero-lateral base of the 
metathoracic legs, and one pair of small caudal gills attached to 
the subanal lobes. In the more immature forms, the caudal gills 
are either absent, or so small as to be easily overlooked. 
Mouth parts. Labrum about four times as wide as long. Man- 
dibles slightly asymmetrical, each with four teeth followed by long 
hairs. Maxillae: first segment of palpus about as wide as long; 
second half again as long as wide; third and fourth subequal, 
each about as long as one and two combined; fifth about three- 
fourths as long as fourth, and half as wide. Galea slender, two- 
segmented, the basal segment a little longer than the apical one, 
which is tipped with a few hairs. Lacinia broad at base and gradu- 
ally tapering to a long incurved tooth, which has at its base a 
second long tooth; this second tooth is followed by a series of 
about six long stout hairs and a series of more slender hairs. 
Labium: first segment of palpus twice as long as wide, the second 
half again as long as first, third about as long as first but much 
more slender; glossae small; paraglossae produced into large 
rounded lobes. 
Little is known about the biology of this species. The nymphs 
occur in pools of streams and have been taken several times from 
Beebe Lake, a small lake formed by an artificial dam in Fall 
Creek, Ithaea, New York. Specimens have been reared as follows: 
Elkhart, Indiana, April 2, by A. Weith; Lake Forest, Illinois, 
April 15, 1902, by J. G. Needham. 
Genus ACRONEURIA Pictet 
The nymphs of this genus are rather large, mostly more than 
an inch in length when fully grown. Body depressed; gills under 
thorax, and some species with anal gills also. Color varying from 
uniform brown to strikingly colored patterns of yellow and 
brown. 
In general appearance these nymphs resemble very closely the 
