INSECTS. 283 



III) Antennae of eleven joints. 



Gen. GEOTRUPES, BULBOCERUS, ELEPHASTOMA, ATHYRIA, LETHRUS. 

 b. Labium entirely covered by the chin. 



Antennae generally of ten joints, of nine in some ; mandibles and labrum less pro- 

 jecting than in the preceding, not seen from above ; internal side of the jaws den- 

 tated. These insects produce a stridulous noise. 



|| Antennae of nine joints. 



Gen. CRYPTODES, MECHIDIA, 

 HI) Antennae of ten joints. 



Gen. PHOBERUS, TROX, HYBOSORA, ORPHNE. 



B. Labrum and mandibles rarely projecting beyond the head ; posterior extremity 

 of the mandibles discovered. 



a. Labium entirely concealed by the chin, and not distinct from it; body rarely elon- 

 gated. 



I) Antennae of ten joints, the last three forming the club ; jaws in the greater num- 

 ber entirely corneous and dentated, or terminated in a coriaceous, hairy lobe. 



XylopUli. 



Gen. ORYCTES, PHILEURUS, SCARAB.&US, HEXODON, RUTELA,CHASMA- 

 DITJS, MACRAPSIS, PELIDNOTES, CHRYSOPHORUS, OPLOGNATHA, CY- 

 CLOCEPHALTJS. 



(HI Antennae of from eight to ten joints, the club in many males formed by the last 

 seven or five, and of the last three in others ; mandibles covered above by the 

 hood, and concealed below by the jaws, the exterior side only being apparent. 



Phyllophagi. 



Mandibles strong, entirely corneous ; extremity of the jaws without teeth or with 

 but two ; antennae of ten joints. 



Gen. ANOPLOGNATHA, LEUCOTHYRJEUS, APOGONIA, AMBLYTERA. 



Mandibles strong, entirely corneous ; jaws many-toothed ; anterior tarsi of the 

 males dilated and furnished with brushes below ; antennae of nine joints. 

 Gen. GENIATIS, (Gematis, Dej.) 



Mandibles strong, entirely corneous ; jaws many-toothed ; tarsi alike and with- 

 out brushes in both sexes. 



L. Club of the antennas of from five to seven leaflets in the males. 



Gen. MELOLONTHA, (antennae of ten joints) ; PACHYFUS, (antennas of nine 

 joints.) 



LL. Club of die antennae of three leaflets in both sexes. 

 O. Antennae of ten joints. 



Gen. RHIZOTROGUS, (Melolontha cestiva ,) AREODES. 

 OO. Antennae of nine joints. 



Gen. AMPHIMALLUS, (M. solstitialis ;) EUCHLORUS, (Anomala, Dej.) 



Internal portion of the mandibles less solid than the other, or membranous ; 

 antennae of nine or ten joints, of which the first three form a club. 

 Gen. OMALOPIA, ANISOPLIA, HOPLIA, MOKOCHELES, MACRODACTYLUS, 



DlPHUCEPHALUS. 



b. Labium projecting beyond the chin, bilobed. 



Mandibles corneous ; jaws terminated by a membranous and silky lobe ; body often 

 elongated, with the hood advanced, the thorax oblong or almost orbicular ; elytra 

 distant or gaping at their junction posteriorly ; antennae of ten joints, of which 

 the last three form the club. 



AnthoUL 

 Gen. GLAPHYRUS, AMPHICOMA, ANISONYX, CHASMATOPTERUS. 



2. Mandibles much flattened, in the form of thin plates or scales, generally almost 

 membranous. 



