Casey — A Revision of the American Paederini. 153 
developed aciculate teeth; eyes very small; neck barely two-fifths as 
wide as the head; anterior tarsi scarcely thickened, not at all spongiose 
beneath; hind tarsi very slender, filiform. Europe......*Mieromedon 
Gular sutures more or less approximate, gradually converging and most 
narrowly separated near the base of the head; species small to moder- 
ately large in size, generally very finely, rather closely punctured and 
only moderately shining; eyes very small; antennae moderately thick, 
gradually enlarged distally; neck about two-fifths as wide as the head; 
hind tarsi moderately slender. Palaearctic and Nearctic regions..Medon 
11 — Gular sutures converging and most narrowly separated basally; species 
small or moderate in size, of rather stout form, shining, the punctures 
fine and well separated; antennae as in Medon; eyes well developed; 
neck rather wide, almost half as wide as the head; prosternum only 
carinate at the posterior cusp; elytra larger than the prothorax; pos- 
terior tarsi moderately slender. Pacific coast regions.....Paramedon 
12 — Body moderately small in size, very slender, dull in lustre but not 
distinctly punctate, parallel, the elytra subequal to the prothorax; gular 
sutures widely separated; paraglossae coarsely, angularly bilobed, the 
ligula simple at apex; palpi nearly normal, the second joint of the 
labial compressed, the fourth joint of the maxillary small; antennae 
moderate in length, slender, filiform, not appreciably enlarged distally, 
the third joint but little longer than the second, the first rather longer 
than the next two combined though but little thicker; eyes very small; 
neck unusually narrow, scarcely a third as wide as the head; proster- 
num strongly carinate. Sonoran.......ccscescecee-oeeee Medonodonta 
Body somewhat stout and more convex, moderately large in size, polished, 
strongly but not densely punctured; gular sutures narrowly separated; 
oral organs nearly as in the preceding, the eyes well developed; anten- 
nae long, rather slender, feebly enlarged distally, the third joint dis- 
tinctly longer than the second, the first somewhat elongate but not 
much thicker; neck two-fifths as wide as the head; elytra Jarger than 
the prothorax; hind tarsi rather longer than usual, moderately slender, 
the anterior noticeably dilated. Pacific coast regions......QOxymedon 
13 — Gular sutures rather approximate, converging, most narrowly separated 
basally.. Body moderately small in size, subdepressed, rather stout, 
subalutaceous, very finely, rather closely punctured, the elytra much 
larger than the prothorax; lobes of the paraglossae rather obtuse at 
apex; third maxillary palpal joint unusually inflated, somewhat com- 
pressed and scarcely longer than the second; antennae rather thick, 
feebly enlarged distally, the third joint but little longer than the second; 
eyes moderately developed; neck scarcely two-fifths as wide as the 
head; prosternum carinate; posterior tarsi short and rather thick, the 
first joint almost as long as the next two combined, the anterior dis- 
tinctly dilated; labrum with four large and conspicuous acute teeth, 
the small deep rounded median notch with a minute obtuse denticle at 
the bottom, the structure throughout nearly as in Polymedon. Appa- 
lachiad TeZiON.+ssscecceccccccccssvceccesccssccee socsseee Tetramedon 
Gular sutures more or less widely separated, parallel or broadly arcuate, 
becoming more widely divergent basally.......sceccececccccccccecceld 
14— Labrum with a small rounded median notch limited by the two inner 
