SCAR AB^EID AE. 145 



Club of antennae elongated in the male. Oryctomorphi. 



Posterior tibiae digitate or festooned at the extremity. Oryctes. 



Group I.— Pentodontes. 



Moderate-sized, robust, convex species, having the head slightly 

 tuberculate, or rather, in our species, with small anterior ridges 

 or teeth, alike in both sexes ; thorax sometimes with a small acute 

 tubercle near the anterior margin, sometimes entirely uniform, 

 convex. 



Two genera occur in our fauna : Ligyrus, generally diffused ; 

 Aphonus, from the Atlantic and Central districts. 



Btridulating organs on the inner surface of the elytra ; mandibles toothed 



externally. Ligyrus. 



Stridulating organs entirely wanting ; mandibles not toothed. Aphohus. 



For the description of our species, see Proc. Acad. Nat. Sci., 

 Philadelphia, VIII, 19. 



Group II.— Oryctomorphi. 



I would refer to this group the very anomalous genus Polymce- 

 chus Lee.,* although, in the opinion of Prof. Lacordaire, it may 

 be placed in the sub-tribe Cyclocephalaa, near Pachylus, a very 

 anomalous genus found in Brazil. It is manifestly a transition 

 form from Dynastini to Melolonthidfe ; but, on account of the 

 form of the clypeus, which is trilobed, strongly margined, with 

 two small apical teeth, and a short transverse carina each side 

 behind, it would seem to belong more naturally in the present 

 sub-tribe,' with which also the narrow mentum agrees. It resem- 

 bles the foreign genera of this group in having- the club of the 

 antennae elongated in the males, but differs by the thorax not 

 impressed, and the strongly toothed outer claw of the middle and 

 hind tarsi. It also agrees with them in the hind tibia? scarcely 

 enlarged at the extremity, and the first joint of the hind tarsi not 

 elevated. It has no organs of stridulation. The mandibles are 

 not toothed externally. 



The only species, P. brevipes, is found in New York and 

 Pennsylvania, but is quite rare. It is oblong-oval, dark brown, 

 seven-tenths of an inch long, with the elytra punctured in rows, 

 becoming confused towards the suture. 



* Proc. Acad. Nat. Sci., Phil., VIII, 23. 

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