June i^oo.] Casey: On North American CoLEOPTE^A. 61 



Prothorax widest at base 2 



Prothorax narrowed at base ; body narrower and lathridiiform 3 



2 — Anterior coxae long and narrow, inclosed within deep oblique fossns and attached 

 more externally, the intermediate and posterior generally with distinct post-coxal 

 plates ; body rounded or oval and convex, generally glabrous ; antenna; II- or 9- 



jointed Corylophini 



Anterior coxae short, oblong ; body pubescent, the pronotum covering the head, con- 

 vex, the edges not explanate and the hind angles greatly produced posteriorly 

 and acute ; antenna; lo-jointed ; abdomen more extensile, with the basal segment 



shorter than usual ; post-coxal plates wanting Sericoderini 



Anterior coxae larger, less deeply imbedded and globular; body more depressed, ob- 

 long or oval, pubescent, the pronotum completely concealing the head, explanate 

 at the margin, the hind angles not produced posteriorly ; antenna il- to lO- or 



possibly 9-jointed Parmulini 



3 — Head completely exposed from above ; anterior coxae small, oval ; antennae 

 9-jointed; integuments sparsely and feebly pubescent .Enigmaticini 



All of these tribes occur on both sides of the continent, but in the 

 first tribe the genera with 9-jointed antennae are the only ones which 

 have thus far appeared in the Pacific district. 



CORYLdPHINI. 



The species of this tribe may be readily known by their rounded or 

 oval convex form and shining glabrous integuments. The genera 

 may be separated as follows : — 



Antennae ll-jointed, inserted between and near the eyes, widely separated at base, 

 the eyes larger and coarsely faceted ; epipleurae rather wide and inflexed 2 



Antennts 9-jointed, inserted more anteriorly and more distant from the eyes, which 

 are smaller and less coarsely faceted ; basal joint shorter ; epipleura; extremely 

 narrow or subobsolete, not at all inflexed ; labrum broadly rounded ; prothorax 

 emarginate at apex, the head in great part exposed ; post-coxal plates very short ; 

 tarsi slender 5 



2 — Head very deeply inserted within the prothorax, the anterior margin of which is 

 evenly rounded and strongly descending ; post-coxal plates large, with rounded 

 outline, the subbasal discal line of the metepisterna very oblique ; labrum rounded 

 or subquadrate 3 



Head partially protruded and less concealed by the overhanging margin of the pro- 

 thorax ; post-coxal plates very short, the subbasal line of the metepisterna nearly 

 transverse ; labrum small, triangular, with the apex acuminate; tarsi dilated 4 



3 — Post-coxal plates of the abdomen more strongly rounded, the external part of the 

 bounding line directed upon the base well within the sides ; third antennal joint 

 elongate, longer than the second Bathona 



Post-coxal plates of the abdomen less arcuate posteriorly, the bounding line extending 

 to the sides of the body ; third antennal joint elongate but shorter than the sec- 

 ond Corylophodes 



