272 t COLEOPTERA OF NORTH AMERICA. 



Four natural groups appear to exist among our genera : — 



Vertex not elevated ; 



2d joint of antennae long. Macrobases. 



2d joint of antennae much shorter than the 3d. Lytt^e. 

 Vertex elevated ; 2d joint of antennae small ; 



Mandibles obtuse. Eupomph^:. 



Mandibles emarginate. Phodag^e. 



Group I.— Macrobases. 



I have separated as a distinct group the species included in 

 Lytta division C. of my synopsis.* The general appearance of 

 the species, and the remarkable sexual characters impressed on 

 the antennae evidence the correctness of the view here taken. 



The eyes are strongly transverse and broadly emarginate ; the 

 antennae are inserted in front of the eyes ; the first joint is usually 

 much elongated, especially in the males, frequently compressed 

 and bent in that sex ; the second joint is larger in the males than 

 in the females, and is generally longer than the third, sometimes 

 much longer, but in Apterospasta the second is a little shorter 

 than the third ; the vertex is not elevated ; the last joint of the 

 maxillary palpi is triangular and obliquely truncate ; the mandi- 

 bles are thick and obtuse, with a small tooth near the apex. The 

 anterior thighs have a sericeous spot of hair on the under surface. 

 The spurs of the hind tibiae are always slender, and the divisions 

 of the claws equal ; the tarsi are pubescent beneath. 



Two genera are separated as follows : — 



Body without wings ; metasternum short. Apterospasta. 



Body winged ; metasternum long. Macrobasis. 



Apterospasta approaches to Henous of the first tribe of this 

 family ; it contains two species, Lytta valida Lee. and L. seg- 

 menta(ta) Say, found in Texas and Nebraska. Macrobasis con- 

 tains several species found in the Atlantic and Central districts ; 

 none have yet occurred in the regions adjoining the Pacific. 



Group II.— Lyttae. 

 The eyes are transverse and broadly emarginate ; the antennae 

 are inserted in front of the eyes, with the second joint much 

 shorter than the third, and except in Pleuropompha, very small ; 

 they are sometimes filiform, sometimes with the outer joints larger 

 and rounded ; the vertex is not elevated ; the last joint of the 



* Proc. Acad. Nat. Sc, Phila., VI. 331. 



