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fraterna, Harr.* Frequent, Central and Southern I[linois. 
nova, Smith.* Rare, Central Illinois. 
corrosa, Lee. Rare, Illinois. 
‘rugosa, Mels.* Common, Central Illinois. 
implicita, Horn.* Frequent, Central and Northern Illinois. 
balia; Say.* Infrequent, Central and Northern Illinois. 
villifrons, Lec.* Infrequent, Central and Northern Illinois. 
‘limula, Horn. Rare, Ilinois. 
hirticula, Knoch.* Abundant throughout State. 
ilicis, Knoch.* Common throughout State. 
crenulata, Frohl.* Infrequent throughout State. 
. inepta, Horn.* Rare, Southern Illinois. 
. tristis, Fabr.* Abundant throughout State. 
The following species will probably be found to occur in [linois: 
L. gracilis, Burm. (Can. to. N. C. and Tex.); L. affints, Lec. (D. C.; 
Kan., Col., Ind. Ter., and Tex.) ; and L. knochu, Gyll. (Mass. to Ga., 
Kean, and. “Dex.). 
Key to the Illinois Species of Lachnosterna.* 
The classification of the June beetles presents unusual difficulty because 
of their general uniformity of appearance and the large number of species, 
and extensive use must be made of the sexual characters, external and 
internal. This difficulty reaches a climax in the group of species allied to 
fusca, which are almost absolutely indistinguishable by any other means. 
One would naturally doubt the validity of such species, but on a careful 
study of these characters, I find them easily recognizable and subject to 
but little variation, and have no doubt of the distinctness of the species 
based upon them. 
A very useful character is the sculpture of the last two ventral seg- 
ments of the male, each species presenting its own characteristic pattern. 
The internal sexual structures of both sexes seem to be a reliable means 
of identifying species. The claspers of the male rest just within the open- 
ing at the tip of the abdomen, and may be easily drawn out and examined. 
It is desirable that specimens should be mounted with the claspers pro- 
truded. In the females and some of the males the two spurs at the end of 
the hind tibia are distinctly articulated and freely movable when fresh; 
but in the majority of the species the males have one spur firmly soldered 
to the tibia, appearing like an acute prolongation of the apical margin. 
The notch or sinuation at the base of this spur is very strong and distinct 
in congrua and hirtiventris, and least developed in gibbosa, which may be 
immediately recognized, however, by its remarkable angulate spur. The 
antennal club of the male is usually much larger than that of the female. 
The antenne are usually ten-jointed, three joints in the club and seven 
in the stem, but several species have normally only six joints in the stem, 
making the antenne 9-jointed. Besides this, there is a tendency to lose 
one joint of the stem in one or even both antenne of individuals of 
either group, so that we may find 9-jointed antenne in species normally 
10-jointed, and 8-jointed antennz in those normally 9-jointed. 
Other distinguishing characters are found in the vestiture, color, and 
punctuation; the clypeus; the outline, margin, and basal channel of the 
thorax; the distinctness of the elytral coste; the length of the antennal 
club; the teeth of the tarsal claws, ete. 
The following key makes extensive use of the characters of the male, 
without which the species could scarcely be identified with any certainty. 
The females may be determined by comparison with the males. The classi- 
fication is based on the excellent monograph of Dr. Horn, “Review of the 
Species of Lachnosterna of America North of Mexico,” in Trans. Am, Ent. 
* Prepared by Mr. C. A. Hart. 
pleat soi sate ea ts egies 
