140 
L. marginalis, Lee.* Rare, Illinois. 
L. fraterna, Harr.* Frequent, Central and Southern Illinois 
L. nova, Smith.* Rare, Central Illinois. 
L. corrosa, Lee. Rare, Illinois. 
L. rugosa, Mels.* Common, Central Illinois. 
L. nnplicita, Horn.* Frequent, Central and Northern Illinois. 
L. ball a, Say.* Infrequent, Central and Northern Illinois. 
L« villifrons, Lee.* Infrequent, Central and Northern Illinois. 
L. limula, Horn. Rare, Illinois. 
L. hirticula, Knoch.* Abundant throughout State. 
L. ilicis, Knoch.* Common throughout State. 
L. crenulata, Frohl.* Infrequent throughout State. 
L. inepta, Horn.* Rare, Southern Illinois. 
L. tristis, Fabr.* Abundant throughout State. 
The following species will probably be found to occur in Illi¬ 
nois: L. gracilis , Burm. (Can. to N. C. and Tex.); L. affinis, 
Lee (D C., Kan., Col., Ind. Ter., and Tex.); and L. knochii , 
Oyll. (Mass, to Ga., Kan., and Tex). 
Key to the Illinois Species of Lachnosterna* 
The classification of the June beetles presents unusual difficulty because 
ot 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 
hut little iariation, 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. 
— he internal sexual structures of both sexes seem to be a reliable means 
ot 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 ex¬ 
amined. It is desirable that specimens should be^ mounted with the 
C l as ?. ers Protruded■ . Ih 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. 
• antenD£e 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 antennas 9-jointed. Besides this, there is a tendency to lose 
the stem in one or even both antennae of individuals of 
. er £ rou P> so that we may find 9-jointed antennae in species normally 
JO-jointed, and 8-jointed antennae 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 costae: the length of the antennal 
club; the teeth of the tarsal claws, etc. 
* Prepared by Mr. C. A. Hart. 
