130 COLEOPTERA OP NORTH AMERICA. 



Fam. XXIV— rhyssodidae. 



Mentum very large, quadrate, bisinuate in front, covering 

 entirely the mouth beneath; palpi short, 8-jointed. 



Maxillifi with two small lobes; palpi short, 4-jointed. 



Antennie inserted under the frontal margin, 11-jointed, 

 joints nearly eqnal, rounded, the first larger, but also 

 rounded. 



Prothorax beneath with the side pieces distinct, the suture 

 running parallel with the lateral margin; coxal cavities 

 closed behind, widely separated. 



Mesosternum very short, side pieces diagonally divided, 

 epimera reaching the coxas. 



Metasternum very large; side pieces very narrow, almost 

 concealed by the elytra. 



Elytra rounded at tip, covering the abdomen, with six or 

 seven deep furrows, or rows of punctures ; scutellum wanting. 



Abdomen with six ventral segments; the first very widely 

 separating the coxa3, broadly triangular; the three anterior 

 ones closely connate. 



Anterior coxa3 small, globular, not prominent; middle 

 coxee globular, small; posterior coxas small, subtriangular, 

 prominent internally, all of them widely separated. 



Legs short; anterior tibiae somewhat dilated, terminated 

 hy two hooks, on the under surface sulcate towards the tip, 

 subeinarginate, and armed above the tip with a spine ; middle 

 and posterior tibias with an internal terminal spine, spurs 

 distinct; tarsi 5-jointed, very slightly pubescent beneath; 

 posterior trochanters prominent, oval. 



Two genera, of singular form, found under bark, constitute this 

 family, which in several of its characters resembles the Carabidae, 

 but yet not so as to belong to the same series. The antennae are 

 composed of equal globular joints; tlie head is strongly con- 

 stricted behind into a neck, and is sculptured with two deep 

 grooves, converging behind; the thorax is long, has three entire 

 grooves, and two short posterior broader ones (Clinidium), or 

 three deep enlire ones, and two finer lateral lines (Rhyssodes); 

 the elytra are deepl}^ grooved in Clinidium, coarsely striato-punc- 

 tate in Ilhyssodes. 



Eyes lateral, rounded, distinctly granulated. Rhyssodes. 



Eyes superior, narrow, scarcely granulated. Clinidium. 



These genera are represented on both sides of the continent, 

 by one species in each region. 



