260 COLEOPTERA OF NORTH AMERICA. 



Group II. — Oryctes (genuini). 



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. 

 The prothorax of the male of Strategus has usually three horns, 

 though sometimes but one small tubercle in both sexes. 



Mandibles not toothed externally. Xyloryctes. 



Mandiblt's strongly toothed. Strategus. 



No species has been found west of the Rocky Mountains. 



Sub-Tribe .3.— Dyiiastiiii (genuini). 



One species of Dynastes found in the Southern States, one in 

 Arizona, and Megasoma Thersites in Lower California represent 

 this sub-tribe in our fauna. The former are of a greenish-gray 

 color, with black spots scattered irregularly over the elytra, the 

 latter is dark brown and pubescent. 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; but in Megasoma it is produced into a spine; there 

 are no stridulating organs. 



Prosternal proces large, hairy. Dynastes. 



Prosternal process moderate, glabrous. Megasoma. 



Sub-Tribe 4.— Phileiirini. 



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 sliort horns or tubercles, the latter with one tubercule in our 

 species, though not so in certain foreign ones; legs alike in both 



