102 THOMAS SAY FOUNDATION 
directed outward, so that the posterior margin is almost at right 
angles with the long axis of the body. Legs long, slender, and not 
very much depressed; outer margins of femora and tibiae with 
a thin fringe of long hair; first and second tarsal segments sub- 
equal, the two together about as long as the third. 
Abdomen nearly cylindrical; cereci long and slender. 
In some of the species there are present three pairs of three- 
segmented, filamentous gills attached to the inner side of the 
ecoxae. These gills are telescopic in nature and may be shortened 
or lengthened. 
Mouth parts of the herbivorous type; the labrum not more than 
half again as wide as long, slightly emarginate in the middle 
of the anterior border which bears a fringe of hairs. Mandibles 
somewhat asymmetrical, with four or five rather blunt teeth; 
these teeth are followed by a molar and a fringe of short stout 
hairs with longer hairs beyond. Maxillae: lacinia triangular, broad 
at the base, terminating in a broad bluntly pointed tooth which is 
followed by a series of long hairs. Galea large, two-segmented, 
reaching to the tip of the lacinia, and bearing at the apex numer- 
ous small tubercles. Maxillary palpus, when fully extended, reach- 
es beyond the tip of the lacinia; first and second segments not 
longer than wide; third segment a little longer than first and 
second combined; fourth a little shorter than third, and the last 
segment about as long as the third; entire palpus very stout. 
Labium much longer than wide; glossae and paraglossae about 
equal in length, although in some specimens the glossae seem to 
be a little longer than the paraglossae; both glossae and para- 
glossae bear at the apex numerous small tubercles, and the para- 
glossae also bear long hairs; labial palpi very short and heavy; 
first segment only about half as long as wide; the second hardly 
longer than wide, and the third very slightly longer than wide; 
entire palpus does not reach beyond the tips of the paraglossae. 
Mentum quite wide; hypopharynx rounded at the tip and extend- 
ing nearly to the tip of the glossae. 
The nymphs of this genus are found in slowly-running water, 
and at times may occur in fresh-water ponds or pools. They are 
herbivorous, feeding entirely on vegetation. The life cycle ap- 
parently occupies but one year; they mature early in spring, 
and in the vicinity of Ithaca, begin to emerge in February. Adults 
may be found as late as April. When ready to transform the 
nymphs crawl up on the vegetation bordering the ponds and 
streams, and cast skins may often be found there. The adults are 
