ON SOME AMERICAN PHYTOPHAGIC EURYTOMIN.E. 
By L. O. Howarp. 
cen years aco. when Prof. F. M. Webster, then a field agent of this 
division, was engaged in studying certain grain-stalk and grass-stalk 
iusects im indiana and Ohio, and at about the time when he succeeded 
in securing the material upon which Dr. Riley established, with his 
assistance, the fact of dimorphism and alternation of generations of 
Tsosoma tritici and I. grande, he collected and reared several other 
species of Zsosoma, and a little later Mr. Koebele, in California, also 
an agent of the division, reared several additional species. At that 
time the writer drew up a rather careful paper on the genus as it was 
then understood, characterizing all the new forms, and had competent 
figures of the most important species prepared. The manuscript 
was then laid aside in the hope that further facts would be ascertained 
concerning the life history of some of the species which would render 
the account more complete. Other matters have interfered, however, 
with the proposed studies, and as the importance of placing the facts 
already collected upon record and of describing and naming the new 
forms seems great, the whole subject has been carefully gone over 
again in the light of recent papers which have been published (espe- 
cially by Mr. Ashmead), and which involve certain generic changes in 
the subfamily Eurytomin, and the results are presented herewith. 
The writer has included in his account only the species which have been 
reared or of which we know the habits with some certainty. There 
are several additional species in Mr. Ashmead’s collection and in the 
collection of the National Museum, but we do not know their specific 
habits, and they are omitted from present consideration on that account. 
The species here treated are included in five genera, the females of 
which may be separated by the following table: 
ANALYSIS OF GENERA. 
Females. 
Metathorax much lengthened. 
Metanotum sloping, rounded behind.-.-.----.----.---------------- ----- Tsosoma 
Metanotum quadrate, abruptly truncate behind....---..------------ Isosomorpha 
Metathorax not lengthened. 
Postmarginal vein longer than stigmal, but not twice as long. 
Parapsidal furrows obliterated posteriorly. ..--...-------------- Decatomidea 
Parapsidal furrows complete, distinct. -.-------------------- Eurytomocharis 
Postmarginal vein twice as long as stigmal..--.-.-----.-------------- Evoxrysoma 
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