Casey — A Revision of the American Paederini. 151 



Gular sutures always separated, sometimes very feebly impressed and occa- 

 sionally altogether effaced and traceable only by differences in sculpture 

 between the intersutural region and the remainder of the under surface 



of the head 3 



2 — Labrum short and very broad, truncate, broadly, feebly sinuate at the 

 middle and having six very small teeth or tooth-like undulations; 

 species very large in size for the present group ; paraglossae coarsely and 

 angularly bilobed; palpi normal, the third joint of the maxillary fully a 

 third longer than the second; eyes moderate; antennae rather thick, 

 filiform, the third joint very much longer than the second; prosternum 

 feebly and obtusely carinate posteriorly; tarsi moderately slender, the 

 basal joint of the posterior distinctly longer than the second, the an- 

 terior distinctly dilated and spongy beneath in both sexes; integuments 

 shining, simply and rather coarsely punctate, the neck one-half as wide 

 as the head; male ventral characters very slight. Sonoran. . Neomedon 

 Labium narrower, more rounded, with four acute and well developed teeth 

 and a small median notch, which is acutely denticulate at the bottom; 

 species moderate in size; paraglossae of the usual form, acutely 

 bilobed; ligula setose at tip; eyes rather small; palpi normal; antennae 

 rather thick, filiform, the third joint only slightly longer than the sec- 

 ond; prosternum acutely carinate posteriorly; tarsi rather short and 

 thick, the basal joiut of the posterior much longer than the second, the 

 anterior thickened but scarcely dilated ; integuments very densely dull, 

 the sculpture rather coarse and extremely dense; neck rather narrow, 

 from rather more than a third to two-fifths as wide as the head; male 



unknown. Sonoran Polymedon 



3; — Labrum bidentate - 4 



Labrum quadridentate 13 



Labrum without teeth, though having the usual small median notch 18 



4 — Antennae with the two basal joints normally thick, the remainder very 



slender, filiform and verticillate; labral teeth small but distinct and 

 approximate, the notch small; species generally dull in luster, with 



close flue sculpture 5 



Antennae normal, equally or subequally thick throughout, sometimes feebly 

 enlarged toward tip 6 



5 — Gular sutures moderately separated, gradually converging and most nar- 



rowly separated toward base; eyes more or less well developed, the 

 neck rather broad but usually less than half as wide as the head; pro- 

 sternum not carinate except posteriorly; tarsi moderately short and 

 somewhat thick, the basal joint of the posterior distinctly longer than 

 the second, two to four decreasing in lergth, the anterior more or less 

 distinctly dilated; species very numerous, small in size, always rather 

 distinctly punctured, the male sexual characters simple, the fifth seg- 

 ment scarcely modified. South America to the warmer parts of North 



America Sciocharis 



Gular sutures very widely separated and mo3t approximate anteriorly, 

 thence widely diverging to the base of the head; eyes rather small; 

 neck nearly half as wide as the head; prosternum not at all carinate; 

 tarsi short and moderately thick, the first joint of the posterior dis- 

 tinctly longer than the second, two to four equal and about as long as 



