78 U.S. NATIONAL MUSEUM BULLETIN 2 79 



Figures 50-59 



50. Omorgus scutellaris (Say.) Extruded rectal mem- 



brane. 



51. Omorgus scutellaris (Say). Caudal aspect of last 

 abdominal segment (anal lobes in nonextruded 

 position). 



52. Trox sonorae LeConte. Extruded rectal membrane. 



53. Trox sonorae LeConte. Caudal aspect of last 

 abdominal segment (anal lobes in nonextruded 

 position). 



54. Trox aequalis Say. Frons. 



55. Trox fascifer LeConte. Frons. 



56. Trox sonorae LeConte. Biforous spiracle. 



57. Omorgus fuliginosus (Robinson). Dorsal aspect of 

 labrum. 



58. Trox scaber (Linnaeus). Frons. 



59. Omorgus monachus (Herbst). Cribriform spiracle. 



