224 NORTH AMERICAN BLATTIDAE 



This Species is much the largest of the present genus. It is 

 closely related to A. rehni, but may be readily separated by its 

 much larger size, distinctive male genital characters, and different 

 form, coloration and pronotal marking, when present, in the female. 



The males exhibit much color variation; specimens with teg- 

 mina, wings and all but the broad pale cephalic margin of the prono- 

 tum, solid blackish, with a perceptible brownish suffusion, are 

 before us from the Rio Grande valley (Brownsville, Eagle Pass). 

 These have been named nigricans by Caudell. The condition is 

 simply the maximum of intensive coloration found in the species, 

 and every gradation to the normal type is found in the series before 

 us. As we have already frequently observed, in the Orthoptera 

 color variations are by no means worthy of varietal significance, 

 and we consequently place nigricans in the synonymy here. 



To the given male characters, we would add the following ob- 

 servations. 



(Waco, Texas.) Interocular width slightly less than, to slightly more than, half 

 the interocellar width. Pronotum with angles usually sharply rounded, some- 

 times quite broadly rounded, as in yl. erratica; this variation sometimes shown on 

 one side and not on the other. Concealed genital hook proportionately very small 

 when compared with that of rehni or erratica, shaft curving gently inward to near 

 distal extremity, which is sharply curved inward, not enlarged, with apex sharp, 

 directed proximad. Dextro-dorsal concealed genital plate, a large, flattened, smooth 

 corneous finger, somewhat arcuate; dextro-ventral concealed genital plate, a large, 

 irregular, corneous disk, strongly concave, with dorsal margins very broadly and 

 strikingly shagreenous. 



The adult female being hitherto unknown we here describe that 



sex. 



9 ; Carrizo Springs, Dimmit County, Texas. (A. Wadgy- 

 mar.) [Hebard Collection.] 



Description of Female. Very unlike male, apterous, size much larger, form sub- 

 orbicular. Dorsal surface roughened and leathery, covered with very short, but 

 stout, minute hairs, most of which are usually rubbed oft", except along the mar- 

 gins of the body. Pronotum broad, cei)halic margin evenly arcuate, at an angle of 

 slightly over 90°, caudal margin weakly produced mesad, with sides broadly con- 

 cave. Supra-anal plate transverse, trai)eziform. with distal angles rounded; mesal 

 third of caudal margin truncate, with an indication of mesal emargination. Sub- 

 genital plate very large, roundly produced mesad. 



