schaeffer: donaciini of the new world. 59 
1 6. Elytral epipleurae, from a postero-lateral view, transversely 
arcuate, wider than the last elytral interval and not limited 
above by a more or less distinct ridge quadricollis Say. 
Elytral epipleurae narrower than the last elytral interval and 
limited above by a more or less distinct ridge 17. 
17. Posterior femora bicolored or entirely rufous 21. 
Posterior femora uniformly metallic 18. 
18. Posterior femora short, extending to or slightly beyond the 
apex of the second ventral segment; body below sparsely 
pubescent with very short hairs, which are generally feebly 
visible on the first ventral segment and not obscuring the 
metallic surface color; eyes small; elytra without coarse 
rugae, intervals finely rugose from base to apex biimpressa Melsh. 
Posterior femora extending to or slightly beyond the apex of 
the third ventral segment; body below moderately densely 
pubescent, pubescence nearly obscuring the metallic surface 
color; eyes moderately large; elytral sculpture variable. . . 19. 
19. Head more deeply narrowed behind and eyes slightly smaller 
than in subtilis; prothorax and elytra wider and more nearly 
of the form of proxima; prothorax always with impressed 
median line and moderately distinct lateral tubercles; 
elytra without coarse, transverse rugae, intervals relatively 
finely rugose from base to apex; last dorsal segment of 
abdomen of both sexes generally emarginate at middle of 
apex distincta Lee. 
Head slightly narrowed behind; eyes moderately large and ' 
prominent; prothorax with or without impressed median 
line and lateral tubercles; elytra with more or less distinct 
coarse, transverse rugae; intervals often densely rugose 
from base to apex or smooth and feebly rugose in about 
basal half but more densely rugose towards apex; last 
dorsal segment of abdomen not or rarely feebly emarginate . 20. 
20. Form elongate; elytra subtriangular and, viewed laterally, 
flattened towards apex; sides of prothorax distinctly con- 
verging behind, lateral tubercles indistinct; median line 
rarely present; antennae more slender subtilis Kunze. 
Form more convex and subparallel; elytra, viewed laterally, 
arcuately declivous towards apex; prothorax scarcely con- 
verging behind, lateral tubercles more or less distinct and 
median line always present; antennae generally stouter. . . tuberculifrons Schffr. 
21. Prothorax anteriorly subtriangularly impressed, impression 
limited behind by a more or less distinct oblique, obtuse 
ridge; lateral tubercles distinctly limited internally by a 
rather wide but shallow impression ; surface finely punctate 
or moderately finely rugose 22. 
Prothorax anteriorly not impressed; lateral tubercles rather 
feebly limited 23. 
22. Third joint of antennae longer than second and as long as the 
