74 NORTH AMERICAN BLATTIDAE 



Other particularly distinctive features are: the proportionately 

 somewhat broader tegmina in males of virginica and uhleriana; 

 the specialization of the cereal joints in males of uhleriana and 

 remarkably distinctive ootheca of that species; the production of 

 the dorsal surface of the male subgenital plate at the base of the 

 dextral style in fulvescens, and the less radiating, nearly longitu- 

 dinal, discoidal sectors in the male tegmina of zebra. The last fea- 

 ture given for Jidvescens is somewhat variable and to a certain 

 degree geographic in character. Such is also true of an unusual 

 cephalic flattening of the head found in divisa and specialization 

 of the cereal joints in both sexes of pensylvanica.^^^ 



Key to Males 



{Primarily based on the Specialization of the Median and First 

 Abdominal Segments) 



A. Dorsal surface of abdomen unsijecialized. 



B. Interocular space no wider than that between ocelli. Head dark colored. 



Sulci of pronotal disk very decided bolliana (Saussure and Zehntner) 



BB. Interocular space much wider than that between ocelli. Head pale. 



Sulci of pronotal disk moderately decided desertae (Rehn and Hebard) 



AA. Dorsal surface of abdomen specialized. 

 B. Median segment alone specialized. 



C. Median segment with a single specialized area. 



D. Specialized area represented by a moderately large, mesal portion sup- 

 plied with minute, scattered hairs virginica (Brunner) 



DD. Specialized area represented by a tuft of agglutinated hairs. 



E. This tuft small and quadrate, remaining portion of segment showing 



little specialization americana (Scudder) 



EE. This tuft larger and much broader, remaining portion of segment 



showing further specialization zebra new species 



CC. Median segment with twin specialized areas. 



D. These specialized areas represented by weakly raised mesal ridges, with 



brief cephalic faces supplied with a heavy tuft of hairs. 



E. Pronotum proportionately shorter, with point of greatest width mesad. 



Tegmina much broader than pronotum. Cerci with inner distal angles 



of sixth to ninth joints acutely but Ijriefly produced. Subgenital plate 



at base of dextral style not elevated uhleriana (Saussure) 



'"^ The instability of these features prevents nominal rerugiiition, though it 

 probably indicates the incipient stages of geographic racial development. 



