IOWA ACADEMY OP SCIENCES. 
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may be reduced with a reasonable degree of certainty to three: 
A. scoparius, B. hirsuta and curtipendula, and from its scarcity in 
a field of nearly pure scoparius its probable host is a Bouteloa. 
This agrees well with its known habitat, which corresponds 
with that of these grasses. 
REVIEW OP THE GENUS DELTOCEPHALUS, 
This genus is distinctively a group of grass-feeding species, 
probably the most important in this relation on account of its 
wide distribution and large number of species occurring 
annually in immense numbers. 
The genus was originally founded by Burmeister, who char- 
acterized it as follows: Vertex acutely triangular, distinctly 
margined; width between eyes scarcely equaling length; front 
broad, convex; vertex flat. Fieber in his synopsis of the Del- 
tocephali adds the presence of two cross nervures between the 
forks of the first sector and the second, as a sub-family char- 
acter. Later writers have omitted the head characters and 
depended upon the cross nervure alone for group separation. 
Mr. VanDuzee, to whose careful and accurate work we owe the 
greater part of our present knowledge of the American Jassidse, 
seems to have accepted and used this character against his own 
better knowledge and judgment, for, in Entomologica Amer- 
icana (vol. V., p. 93) he says: “This apparently trivial and not 
infrequently variable character seems almost inadequate for use 
in separating these two genera, but, correlated as it is with 
other structural peculiarities, of which it is the most pro- 
nounced, it appears to answer well the purpose of its employ- 
ment, and is much used by Fieber and other European entomol- 
ogists in synoptical arrangements of the genera.” A few years 
later he described Atliysanus instabilis, extrusus and sexvittatus, 
placing them correctly in that genus despite the fact that most 
of the types exhibited the two nervures, thus showing that he 
appreciated the true generic character. The next year, how- 
ever, he again yielded to the demands of this variable char- 
acter and redescribed D. nigrifrons as Thamnotettix perpunctata, 
although evidently appreciating their specific affinity, as seen 
by the following extract: “This insect, though quite distinct 
generically from D. nigrifrons^ is difficult to distinguish in spe- 
cific characters; the markings are almost identical, and the 
form of the facial and genital pieces differ but little.” Dr. 
Melichar, in his recent work on The Homoptera of Middle 
