152 Trans. Acad. Sci. of St. Louis. 



wide, the anterior not in the least dilated or thickened ; species very 

 minute, not distinctly punctured; male sexual characters nearly as in 

 Sciocha7'is, except that the apex of the fifth segment is lobed in the 

 middle. Southern Atlantic States Sciocliarella ' ^r ?. 



6 — Labral teeth small and inconspicuous; prosternum never carinate 



throughout its length except in a few abnormal members of Medon.. 7 



Labral teeth long, acute and very conspicuous; prosternum carinate 



throughout its length; gular sutures converging and most narrowly 



separated basally 12 



7 — Basal joint of the posterior tarsi equal in length to the second, the 



first four short and subequal, the anterior very slightly dilated; palpi 

 normal ; gular sutures rather narrowly separated, evenly, feibly arcuate, 

 very rapidly diverging at base, most narrowly separated at a little be- 

 fore the middle; antennae rather thick, gradually enlarged distally, 

 the third joint distinctly longer than the second; eyes moderate; neck 

 about half as wide as the head; prosternum not at all carinate at any 

 point; integuments very coarsely, densely sculptured and dull, the 

 species small in size. Nearctic regions, east of the Rocky Mountains. 



Trachysectns > >~ °i 

 Basal joint of the hind tarsi distinctly longer than the second, the tarsi 

 more elongate 8 



8 — Labrum with a rather broad sinus at the middle including the two teeth, 



which are very small and not as anteriorly prominent as the sides of 

 the labrum; species small, with the elytra very small, shorter and nar- 

 rower than the prothorax; eyes rather small; neck two fifths as wide 

 as the head; gular sutures well separated and .subp.irallel but obsolete 

 or very feeble; antennae short, moderately thick, filiform, not en- 

 larged di:^tally, the basal joint thicker than the remainder; prosternum 

 rather strongly carinate except anteriorly; posterior tarsi very slender 

 and filiform, the anterior slightly dilated; integuments rather coarsely, 



densely sculptured and dull. Appalachian region Heinimedou >^° 



Labrum with a narrower mt^dian notch, the two teeth more advanced than 

 the lateral parts of the edge and not included within the sinus 9 



9 — Anterior tarsi not dilated but only more or less strongly thickened; sex- 



ual characters very feeble 10 



Anterior tarsi strongly dilated, especially in the male; sexual characters 

 strongly marked 11 



10 — Gular sutures distant, broadly arcuate, becoming very widely diverg- 



ent toward base and most narrowly separated well before the middle; 

 species small, slender in form, polished and sparsely punctate, the 

 elytra subequal to the prothorax in size; antennae moderately thick, 

 somewhat enlarged distally; labrum very broadly, angularly emarginate, 

 with a small feeble median sinus, the teeth very minute; eyes rather 

 well developed; neck a little less than half as wide as the head; ante- 

 rior tarsi spongiose beneath in both sexes; hind tarsi slender and fili- 

 form. Europe *Hypomedou 



Gular sutures of the same form as in Hypomedon but subobsolete; species 

 miaute, slender, polished and sparsely, rather coarsely punctate, the 

 elytra shorter than the prothorax; antennae normal in structure; lab- 

 rum small, truncate, with a distinct rounded median sinus and two well 



