88 



COLEOPTERA OF NORTH AMERICA. 



Antennae ll-jo1nted. 2. 



Antennae 10-jointed. Decarthron. 



2. Abdomen margined ; tarsi with a single claw. . o. 

 Abdomen not margined ; tarsi with two nnequal claws. Batrisus. 



3. Antennae with the last three joints larger. 4. 

 Antennae with only the last joint large. 6. 



4. El_y«tra with a dorsal stria. f>. 

 Elytra without striae, prothorax not foveate. Pselaptus. 



.5. Elytra with dorsal stria ; abdomen broadly margined. Bryaxis. 



JKlyti-a without dorsal stria ; abdomen finely margined. 



Scalenarthrus. 

 Eutrichites. 

 Bupsenius. 



6. Antennae long, body pubescent. 



Antennae very short ; body glabrous. 



With Batrisus we have combined Arthmius Lee, described as 

 having but a single unguis; renewed examination, with a power- 

 ful microscope, has shown that there is a second very small unguis 

 present. The antennae are frequently very different in form in 

 the sexes of the same species of Bryaxis and Batrisus; these two 

 genera are also represented in the Pacific district. Scalenarthrus 

 occurs in Arizona. 



Tribe II.— EUPLrECTIXI. 



The insects of this tribe have a more depressed and linear form 

 than is seen in the preceding tribe, and approach thus to the 

 next family. The anteunte are always distant, and the abdomen 

 strongly margined. The posterior coxae are conical, prominent, 

 and contiguous. The abdomen has six distinct ventral segments. 



Tarsi with two uneqiral claws. 2. 



Tarsi with a single claw. 3. 



Tarsi with two equal claws. Faronus. 



2. Antennae straight, 1st joint not elongated. Trichonyx. 

 Antennae geniculate, 1st joint long. Rhexius. 



3. Front not prolonged ; antennae quite straight. 4. 

 Front narrow prolonged ; antennae feebly geniculate. Rhinoscepsis. 



4. Last three joints of antennae gradually wider; 2d ventral segment not 



longer than 3d ; body depressed. 5 



Last joint of antennae very large ; 2d ventral segment elongated ; body 



more convex. Trimium. 



5. Eyes distinct. Euplectus. 

 Eyes wanting. Eutyphlus. 



