6 U.S. NATIONAL MUSEUM BULLETIN 2 79 



and LeConte (1854). He is the first to have recognized the difference 

 in the pattern of the stridulatory teeth on the maxillae of the two 

 groups. 



Incertae Sedis 



Perris (1877) described the larva of Trox hispidus Laichart. He 

 figured the left maxilla, left mandible (dorsal aspect), right mandible 

 (lateral aspect), left antenna, posterior segments (posterior view), 

 and leg of T. hispidus. The figures, however, are not very detailed. 



Systematics 



A comprehensive monograph on the adults of the genus Trox in 

 North America was published by Vaurie in 1955. Vaurie separated the 

 species of Trox into five groups: scaber, terrestris, tuberculatus, untstriatus, 

 and suberosus. A checklist of the species grouped according to Vaurie 

 is presented in table 1. Species whose larvae are now knov/n are 

 marked with an asterisk. 



Two additional species were described by Howden and Vaurie in 

 1957. These species were T. floridanus and T. howelli, and they are 

 included in their respective groups in table 1. 



Other major treatments of the adults of Trox include the following: 

 Palearctic Region (Balthasar, 1936), Africa (Haaf, 1953), Africa and 

 Asia (Haaf, 1954a), Australia (Haaf, 1954b), and South America 

 (Vaurie, 1962). 



Vaurie (1955) recognized that the suberosus group was quite distinct 

 from the other four groups in North America and presented a table 

 listing ten characters which distinguished the adults of this group from 

 those of the other groups. 



On the basis of the larval systematics and recent work on the 

 morphology and cytogenetics of the adults, the writer has restored 

 Omorgus to generic status to include those species in Vaurie's suberosus 

 group in North America. The genus Omorgus was first proposed by 

 Erichson (1847). Trox suberosus Fabricius was later designated by 

 Lacordaire (1856) as the type. LeConte (1854) followed Erichson in 

 this separation, placing 1 1 species from North America in the genus. 

 Subsequent workers, however, considered Omorgus as synonymous with 

 Trox^ as a subgenus of Trox, or as the suberosus group within the genus 

 Trox. The characters supporting the above separation are presented 

 in table 2. These are in addition to those characters listed by Vaurie 

 (1955) in her monograph on the adults. Distinguishing characters are 

 present in all life stages : egg, larva, pupa, and adult. The writer makes 



