184 COLEOPTEaA OF NORTH AMERICA. 



The genera ^Eolus and Heteroderes, adopted by Candeze, 

 appear to be untenable, and heterogeneous; our species are 

 therefore referred to Monocrepidius, removing to Drasterius 

 those with simple tarsi, which were formerly included in the 

 same genus. 



Group V. — Dicrepidii. 



The strongly margined front, the prosternal sutures, excavated 

 in front, and concave outwards, and the tarsi with lobes beneath 

 the seOond and third joints, will distinguish this group. The 

 species are elongate, brown, hairy insects, with strongly serrate 

 autenuEe, sometimes even pectinate in the males. Thecoxal plates 

 are strongly dilated inwards, and toothed. They are found in 

 the Southern States and Texas, and belong to two genera : — 



Mesosternum horizontal ; anterior part of front with two crests, uniting 



above with the frontal margin. Dicrepidius. 



Mesosternum oblique ; front not crested. Ischiodoiitus. 



To the latter genus belong Elate?- solealus Say, and other 

 species. Tricrepidius Motsch. is also an Isehiodontus, probably 

 /. ferreus. 



Group VI. — Elateres. 



In this group are species having the front convex and mar- 

 gined; the thorax always narrowed in front; the prosternum 

 not very wide, with the sutures distinctly double, and sometimes 

 excavated in front, straight or concave outwards; the posterior 

 coxal plates narrow externally, suddenly dilated internally, and 

 toothed at the origin of the thighs; the tarsi not dilated or lobed 

 (the anterior ones in Blauta very slightly so), and the claws entire. 



Our genera are : — 



Prosternal sutures excavated in front ; 



Joints 1-4 of the tarsi gradually increasing in length ; 



Tarsi spongy beneath, the anterior one slightly lobed. Blauta. 



Tarsi ciliate beneath, entirely simjile. Elater. 



First joint of the tarsi as long as the three following united ; 



Second joint of antennae very small, third large triangular. 



Elatrinus. 



Prosternal sutures not excavated in front ; 



Third joint of antenuje longer than the second. Drasterius. 



Second and third joints of antennae small, equal. Megapenthes. 



Drasterius is united by DuVal with Cryptohypnus, but the 

 narrower pi'osternum, with double sutures, distinguishes it very 



