ANNALS 
OF 
The Entomological Society of America 
Volume V UN 9 1e2 Number 2 
HOMOLOGIES IN THE WING-VEINS OF MAY-FLIES. 
ANNA HAVEN MorGANn.* 
The following paper is an attempt to homologize the wing- 
veins of May-flies by a study of the trachez which precede them 
in the nymphal wing-pad. 
The venation of May-flies has been many times discussed 
but only one work, that of the well known “‘ Wings of Insects”’ 
by Comstock and Needham, has approached it from the stand- 
point of tracheation. This work suggested the present study. 
At the outset I wish to express my indebtedness to Professor 
J. H. Comstock and Professor J. G. Needham for their many 
valuable criticisms. The work was done under the supervision 
of Professor A. D. MacGillivray, and while he disagrees with 
some of the interpretations herewith presented his constant 
interest and advice have made this study possible. 
Material and Methods. 
The genera with which this study deals are Epeorus, Iron, 
Ameletus, Ephemera, Blasturus, Hexagenia, Polymitarcys, 
Ephemerella, Siphlurus, Callibztis, Chirotonetes, Heptagenia, 
Leptophlebia, Choroterpes, and Cznis. Nymphs belonging 
to these fifteen genera were collected through the months from 
April to July inclusive, in the streams about Ithaca. They. 
present as wide a range of variation as it was possible to obtain. 
The nymphs selected were those nearly matured whose wing- 
pads bore traces of venation easily seen with a hand lens. 
These were supplemented by younger nymphs showing trachea- 
tion only. Recently molted nymphs were used, since the wings 
of these lie flat upon the slide and both tracheation and venation 
show with great clearness. The method of preparation was 
that of the simple glycerine jelly mount. Nymphs were kept 
at hand in a dish of water. The wing-pad of one of the nymphs 
*Entomological Laboratory, Cornell University. 
89 
