MONOTOMIDAE. 85 



the males, 5-jointed in the females; the males have also a sixth 

 dorsal segment. They are found under bark. One genus, Rhi- 

 zophagus, constitutes the tribe, and is represented on both sides 

 of the continent. 



Fam. XVI.— MONOTOMIDAE. 



Mentum moderate, subquadrate, rounded or subangulated 

 in front ; ligula partly corneous, prominent ; labial palpi 

 short, 3-jointed, first joint very small. 



Maxillae exposed at the base, with two lobes, the outer 

 one long, slender, scarcely ciliate at tip, the inner one larger, 

 ciliate internally and at the tip ; maxillary palpi 4-jointed, 

 the first joint very short. 



Eyes strongly granulated, rounded. 



Antennas inserted under the sides of the front, behind the 

 mandibles, 10-jointed, the last one or two joints forming a 

 club. 



Head tolerably large, flat, suddenly but slightly constricted 

 behind; front broadly lobed between the mandibles, which 

 are short, acute, and fringed with membrane internally ; la- 

 brum very short, not distinct; mandibles short, robust, acute 

 at tip, with a small subapical tooth ; internal margin fringed 

 with hair. 



Prothorax with the side pieces not separate, prosternum 

 entire, coxal cavities small, broadly closed behind. 



Mesosternum short, emarginate behind ; side pieces large, 

 diagonally divided ; epimera attaining the coxae 



Metasternum large, side pieces narrow. 



Elytra truncate behind, leaving the last dorsal segment 

 exposed. 



Abdomen witn five free ventral segments, the first and 

 fifth elongated. 



Coxa3, anterior small, rounded, separated; middle rounded, 

 separated by the sternum ; posterior transverse, separated. 



Legs moderate; tibia? nearly linear, with distinct terminal 

 spurs, and a few small spines about the tip; tarsi 5-jointed, 

 the joints 1 — 3 slightly dilated, and covered beneath with 

 long hair, the fourth narrower and smaller, the fifth longer 

 than the others united, with simple ungues. 



Small, depressed insects, found mostly under bark of trees. 

 Tlu.')- resemble closely in characters and appearance the tribe 



