304 COLEOPTERA OF NORTH AMERICA. 



Pionotum transversely excavated at the sides near the base, prosternum 

 perpendicuLar at tip, niesosternurn usually convex in front. Cyllene. 

 Mesosternuni oblique or nearly flat, prosternum declivous at tip, not per- 

 pendicular, pronotuna not excavated at the sides, but only rounded, 

 and constricted at base ; 

 Antennae compressed, subserrate. Plagionotus. 



Antennae filiform ; 



Mesosternum declivous. Calloides. 



Mesosternum nearly flat, episterna narrower. Arhopalus. 



Plagionotus (Gh/cobius Lee.) contains C. spectosvs Say, a large 

 black and yellow species which infests the sugar maple. 



Calloides Lee. contains C. nobilis Harris, a large species of 

 the Atlantic States, and the nearly allied C. Lorquini Buquet, 

 of California. Arhopalus Serv. (Saroseslhes Thomson) contains 

 only C. fulminans Fabr. 



Grroup II. — Clyti. 



The head is larger than in the Cyllenes, and the front much 

 longer, sometimes perpendicular, and quadrate; the antennas are 

 always short, not very different in the sexes, filiform, or slightly 

 thickened externally; the episterna of the metathorax are usually 

 wide, and the epimera are produced over the angles of the 1st 

 ventral segment, the intercoxal process of which is acute-. The 

 thighs are usually clavate, the hind pair frequently very long, 

 and occasionally spinose at tip; the first joint of the hind tarsi 

 usually very long. 



Front roianded, declivous, thighs not spinose at tip, episterna of meta- 

 thorax vride ; 



Head not carinated. Clytus. 



Head carinated. Xylotrechus. 

 Front quadrate, perpendicular ; head not carinated ; 



Episterna of metathorax wide. Plagithmysus. 



Episterna of metathorax narrow. Clytanthus. 



Clytus is represented by C. marginicoUis Lap. in the Atlantic 

 States, and C. lanifer Lee. in Arizona. 



Clytanthus by C. ruricola Oliv. and albofasciatus Lap. in the 

 Atlantic States. 



The other two genera are distributed over our whole territory, 

 and contain many species. Plagithmysus Motach. is the same 

 as Neochjtus Thomson. 



