H. M. PARSHLEY 
Thus species which are closely similar, for instance in antennal 
structure, may differ widely in genital characters, and in general 
we note a low degree of correlation if we examine the various 
species with respect to any two or more of the important specific 
criteria. These conditions are a source of satisfaction in one 
respect at least; they would seem to preclude any attem])t to 
establish “new” genera at the expense of Aradiis. I am (piite 
aware that the grouping adoi)ted is unsatisfactory in many par- 
ticulars; its correlation with Kiritshenko’s arrangement of the 
palacarctic species Icjivcs much to be desired; l)ut a fully accept- 
able system of groups cannot be established without a com- 
prehensive study of materials rejiresenting the species of the 
world, a study wdiich no one is ready to undertake at present. 
The American species, fully listed further on, may be grouped 
according to the subjoined scheme. 
Aequalis Group. — Antennae slender, the second and third seg- 
ments erpial in length and cylindrical; pronotal and abdominal 
margins entire; granulation of body fine. 1 his group, like the 
four immediately following, contains a single species not closely 
related to others and causing disturbance if jilaced elsewlu're 
than at the beginning. 
Crenatus Group. — Pronotal margins serrate; abdominal mar- 
gins strongly crenate; gramdation very coarse; antennal chai- 
acters much as in the preceding. 
QuadriUneatus Group. — Third antennal segment strongly en- 
larged; pronotal structure agreeing in general with the preceding; 
genital characters distinctive. 
Am}>liatus Group. — Antennae cylindrical, the third segment 
long, yellow in apical half; pronotum as in the tw’o precetling; 
female genitalia peculiar. 
Montanus Group. — Antennae moderately stout, about ecpial 
in thickness to front femora, the second segment proportion- 
ately short, leading toward the next group. 
OrnatuH Group. — Antennae very stout, clavate, generally rough- 
ened; form of body broad; corium strongly dilated at base; colora- 
tion often variegated. Ornatus is isolated by ])ronotal and genital 
structure. The four species following it have' oblicpu', sei'iate' 
TRAN.S. AM. EXT. SO(’., XLVII. 
