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 "Micromotion 



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 region?.. Medon 



11 — Gular sutures convergingandmost 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 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 larger than 

 the prothorax; hind tarsi rather longer than usual, moderately slender, 

 the anterior noticeably dilated. Pacific coast regions Oxymedon 



13 — Gular sutures rather approximate, converging, most narrowly separated 



basally. Body moderately small in size, subdepressed, rather stout, 

 subalutacecu?, 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- 

 lachian region Tetramedon 



Gular sutures more or less widely separated, parallel or broadly arcuate, 

 becoming more widely divergent basally 14 



14 — Labrum with a small rounded median notch limited by the two inner 



