90 Rowland M. Shelley 



8-11. Kohlrausch, 1881:130. Meinert, 1886:208-209. 

 Opisthomega spinicauda: Saussure and Humbert, 1872:200. 

 Opisthemega insulare Meinert, 1886:209-210. Haase, 1887:79. 

 Theatops spinicaudus: Bollman, 1888a:6; 1888c:341. Chamberlin, 1902:41; 



1920:10; 1928:153. 1942:185; 1944^:33; 19446:177-178. Kraepelin, 



1903:65. Brolemann, 1904:244. Crabill, 1950:201; 19556:39. 



Summers, 1979, Figs, 7-8. Shelley, 1987:505-506, Figs. 4, 13. 



Summers et al., 1980:245; 1981:59. 

 Theatops spinicauda: Bollman, 1893:170. Pocock, 1895:28. Brolemann, 



1896:50-51. Attems, 1930:253. Bucherl, 1942:326. Crabill, 1955c:157. 



Kevan, 1983:2945. 

 Theatops posticus (nee Say): Brimley, 1938:50, in part. Wray, 1950:156, 



in part; 1967:156, in part. 



Type specimens. Neotype (NMNH) collected by an unknown person 

 on an unknown date in Chicago, Cook County, Illinois. A vial at 

 the ANSP, supposedly containing a paratype taken by R. Kennicott 

 in southern Illinois, is empty, and the holotype is not known to exist. 



Diagnosis. Ultimate tergite without median suture or with only 

 minute vestige anteriad; ultimate legs dorsally with a distomedial spur 

 on each prefemur (Figs. 7-9). 



Variation. I examined over 250 specimens and observed unreported 

 variation along the inner surfaces of the caudal legs. This surface is 

 generally flattened, particularly on the prefemur and femur, thus forming 

 a ridge along its dorsal and ventral edges. These ridges are highly 

 variable, and the dorsal surfaces vary from unadorned, as in an individual 

 from McDowell County, North Carolina (Fig. 7), to scalloped, as in 

 a specimen from Polk County, Arkansas (Fig. 8), to scalloped with 

 minute teeth, as in one from Haywood County, North Carolina (Fig. 

 9). The ventral ridges are more variable and display conditions with 

 one or more small, fine teeth on the prefemora and, in a few specimens, 

 the femora. Moreover, these teeth also vary in size from sharply acuminate 

 spurs to minute denticles. The most common condition, with no ventral 

 spurs or teeth is shown by an individual from McDowell County, North 

 Carolina (Fig. 19); eleven variants are depicted in Figures 20-30. This 

 variation does not conform to an observable geographic pattern; it 

 occurs sporadically in both areas occupied by T. spinicaudus. The medial 

 borders of the caudal coxopleurae are slightly elevated and prolonged 

 caudad, but there is a darkly pigmented subapical spot and a suggestion 

 of a tooth on nearly all specimens. Individuals from McDowell County, 

 North Carolina, and Polk County, Arkansas, have two distinct teeth 

 at this position (Figs. 19, 28), those in the former being larger and 



