REPORT OF THE STATE ENTOMOLOGIST 1907 307 
to hold this as an adequate explanation of the origin of these 
structures, when one considers the very tortuous courses taken 
_ by these fili in the male Asphondylia for example, or the bizarre 
' form presented in Winnertzia. Furthermore, if these structures 
| were originally the thickened margins of lamellae, we would 
expect traces of a membrane in some of the lower forms such, 
| for example, as the females of Dasyneura, Rhabdophaga and 
| Lasioptera. There appears to be no trace of any such remnant, 
| and we are therefore led to believe that these organs may be 
_ hypodermal structures which, through a process of development, 
have migrated from the interior of the antennal segment, be- 
coming external, and thus greatly increased their value as 
auditory organs. An alternative explanation is that the cir- 
cumfili are simply specially modified setae which have become, 
in some unknown manner, most intimately connected one with 
the other. 
SU DIES IN. CECI DOM DAVE 
The following matter relating to the Cecidomyiidae represents 
only a small portion of our work upon this group. It is pub- 
lished as a preliminary contribution to the classification of our 
American forms. The tables for the separation of the major groups, 
genera and species have been sorely needed in the past, and will 
undoubtedly have a most important influence on all subsequent work 
in this extremely interesting and very important group. 
PRELIMINARY KEYS FOR THE RECOGNITION OF CER- 
TAIN CECIDOMYIIDAE 
The following diagnoses and keys should prove of consider- 
able service in identifying many of the American species be- 
longing to this exceedingly interesting group. They are to be 
regarded as tentative, since it has been impossible for us to 
go over the entire material in a thorough manner, and further 
study may lead to considerable modification in our views. 
Keys to subfamilies and tribes 
a Metatarsus longer than the following segment; five tarsal segments and 
at least four long veins 
DeounhiielOmerveln hESente. sick sense. Subfamily LESTREMIINAE 
GOUT leaVieliankOnIRe Uiveranise. care etre dee a Tribe LESTREMITNARIAE 
6G Mobinil Wenn Chinn onsen eacce cee Tribe CAMPYLOMYZARIAE 
aa Metatarsus usually longer than the following segment; at least three 
HON GU VEINS tN hice eG sincnncidnios Subfamily HETEROPEZINAE 
aaa Metatarsus always shorter than the following segment; wings with three 
OigOUMlONenVeiiSvec meets. Rae Se Subfamily CECIDOMYIINAE 
