234 PROCEEDINGS OF THE NATIONAL MUSEUM vol. i04 



Fore tibia of male with the anteriormost of the 6 or 7 teeth of the 

 outer margin expanded forward and bifurcate. In both sexes there 

 are small teeth on a ridge on the inner flattened surface of the foretibia. 

 Dorsally there is a raised dorsal longitudinal carina extending along 

 the inner edge, with a small sharp extension inward, almost onto the 

 base of the penultimate tooth. Closely adjacent row of setae only 

 interrupted by the small inward carinal extension. External face of 

 tibia of mesothoracic leg with three complete transverse carinae, 

 tibia of metathoracic leg with three, sometimes four, complete trans- 

 verse carinae, with two or thi'ee partial carinae. Posterior edge of 

 hind femur of male produced into a tubercle near coxa, which also 

 protrudes slightly posteriorly. Tarsal claws similar in both sexes. 



Genital capsule and genitalia of male well developed (pi. 5, fig. 2), 

 rather similar to that of egeriei, but generally less elongate. 



Variation within the species is considerable, but apparently is 

 not due to population differences. Size and shape of clypeus and 

 pronotum are extremely variable. 



This species can be easily distinguished by its finely alutaceous 

 dorsal siu-face, imparting a dull appearance to its brown or black 

 color. Also, the lack of striae, fine dense clypeal punctures, piceous 

 antennal club, and structure of male genitalia (pi. 5, fig. 2) will 

 dehmit the species. 



Geotrupes opacus Haldeman has been collected in moderate numbers 

 in sandy localities from South Dakota southward to Texas and from 

 Ohio westward to Colorado. 



Brown (1927, p. 28) mentioned that opacus could be collected from 

 August to May in sandy localities in Payne County, Olda. Knaus 

 (1916, p. 81) recorded taking three specimens on May 7 in the sand 

 hills near Medora, Kans. One of the longer accounts of the species 

 was published by Jones (1886, p. 80), in which he mentions finding 

 in November a number of specimens under some fresh dung along 

 the roadside between Manhattan and Salina, Kans. He observed 

 that, "I have almost always taken it where I have found no other 

 scavengers at work, except Aphodius, and a few Staphylinus perhaps, 

 and I have always taken it either very early in spring or late in the 

 fall. Generally, I have taken it on low bottom land, or on sand bars 

 in the river, where cattle are wont to drink . . . ." 



There are a few other desultory notes concerning the adults, but 

 nothing has been published on the life history of the species. 



Specimens examined: 128 males. 111 females. 



ARKANSAS: 18 males, 12 females. Hope, Imboden, Marion County; (2) Sep- 

 tember, (6) November. 

 COLORADO: 1 female. No data. 



