178 MEMOIRS ON THE COLEOPTERA 



resemble some Cyclocephalids in general habitus and in the more 

 nearly filiform tarsi. At the other end of the series Bothynus and 

 Anastrategus lead directly to the Oryctini in habitus and general 

 structural characters. The Cheiroplatids are so aberrant in many 

 ways, that the propriety of erecting for them a distinct tribe is not 

 wholly questionable, but it would be almost as difficult to place 

 such a tribe in harmonious succession with the others as in the 

 case of Oryctomorpha. The known American genera may be 

 arranged as follows: 



Propygidium moderate in size, the pygidium sometimes greatly developed, 



generally having its upper margin arcuate, at least in the female. .2 



Propygidium large, sinuating the base of the pygidium; anterior tarsal 



claws variable 12 



2 Anterior tarsi (cf ) with swollen claw-joint, the anterior claw broad, 

 abruptly bent at base and variously modified at tip; body oblong, 

 convex, moderately large in size; mandibles distinctly exposed and 

 externally tridentate or bidentate; stridulating organs as in Ligyrus. 



[Type Scarabccus relictus Say] Ligyrodes 



Anterior tarsi slender and with simple claws in both sexes 3 



3 Pygidium simple in both sexes 4 



Pygidium (9) transversely tumid at or above the middle; mandibles 

 well exposed at the sides; clypeus narrowly rounded or subprominent 



at tip; body of rather large size 1 1 



4 Mandibles distinctly exposed externally, usually tridentate; clypeus 



reflexed at the extreme apex 5 



Mandibles hidden, small; clypeus reflexed behind the apex 8 



5 Clypeus bidentate at apex 6 



Clypeus unidentate at apex 7 



6 Ligula with sharply elevated side margins; mandibles bidentate; 

 stridulating organs feebly developed. [Type Heteronychus humilis 



Burm.] Euetheola 



Ligula simple not margined at the sides; stridulating organs well de- 

 veloped. [Type Scarabceus gibbosus DeG. (Podalgus variolosus 



Burm.)] Ligyrus 



7 Body nearly as in Ligyrus, except that the pronotal impression is 

 relatively larger and deeper. [Type Ligyrus ruginasus Lee.] 



Oxygrylius 

 8 Pronotum without an anterior impression in either sex; stridulating 



organs wanting 9 



Pronotum with an anterior impression (cf), wholly wanting (9 ) 10 

 9 Post-apical transverse carina of the clypeus entire. [Type Bothynus 



pyriformis Lee.] Pseudaphonus 



Post-apical carina tridentate. [Type Scarabceus tridentatus Say] 



Aphonus 



10 Post-apical elevation medially sinuate to transverse; body more 

 cylindric than in the two preceding genera, at least in the male, 

 though not always in the female. [Type 0. cuUripes Fairm.] 



Orizabus 



