146 COLEOPTERA OF NORTH AMERICA. 



Group III. — Oryctes (gemiini). 



Large insects, having, in our genera, the mandibles prominent, 

 and sometimes toothed externally, sometimes simple ; the middle 

 and hind tarsi expanded at tip, and truncate in some, digitate in 

 others ; first joint of hind tarsi elevated. Our genera possess 

 stridulating organs, covering the greater part of the propygidium. 

 The head is horned in the male and tuberculate in the female of 

 Xyloryctes, but has only two very minute tubercles in Strategus. 



Mandibles not toothed externally. Xyloryctes. 



Mandibles strongly toothed. Strategus. 



No species has been found west of the Rocky Mountains. 



Sub-Tribe 3. — Dytiastini (genuini). 



One species, Dynastes Tityus, of large size, found in the South- 

 ern States, alone represents this sub-tribe in our fauna. It is of 

 a greenish-gray color, with black spots scattered irregularly over 

 the elytra. The characters of the tribe are : — 



Labial palpi inserted on the sides of the mentum, which is acu- 

 minate in front ; mandibles prominent ; head armed with horns in 

 the male, tuberculate in the female ; thorax horned in the male, 

 simple and not impressed in the female ; anterior feet longer in 

 the males. In Dynastes the first joint of the posterior tarsi is 

 not elevated, and there are no stridulating organs. 



Sub-Tribe 4.— Pliileurini. 



This sub-tribe, of which we possess but the genus Phileurus, is 

 at once distinguished from the others by the labial palpi inserted 

 behind the mentum. Other characters are : the mandibles promi- 

 nent; head and prothorax alike in both sexes, the former with 

 two short horns or tubercles, the latter tuberculate in our species, 

 though not so in certain foreign ones ; legs alike in both sexes ; 

 hind tibia? digitate or truncate at tip, not expanded; first joint 

 of hind tarsi elevated ; stridulating organs on the inner snrface 

 of the elytra, along the lateral margin. 



In Phileurus the mentum is of moderate size, oval, slightly 

 emarginate in front, and the first joint of the hind tarsi is pro- 

 longed into a spine at the extremity. 



Four species are known in our fauna, one of which, P. valgus, 



