220 NORTH AMERICAN BLATTIDAE 



B. Transverse clypeal swelling of face deep. Body covered with minute hairs; 



longer hairs along the margin, particularly cephalad. Cephalic femora with 



ventro-cephalic margin hairy proximad, succeeded in distal half by a rather 



closely set row of short, chaetiform spines. 



C. Size large to medium, form suborbicular. (General color blackish; cephalic 



margin of pronotum often rather narrowly buff, the caudal margin of this 



marking brace-shaped.) Arenivaga bolliana (Saussure) 



CC. Size medium to rather small, form decidedly more elongate. 

 D. Form elliptical. General color immaculate reddish brown. 



Arenivaga rehni new species 

 DD. Form broad ovate. General color reddish brown, often narrowly paler 

 mesad along cephalic margin of pronotum. 

 E. Limbs more elongate and slender. Segments of abdomen normally 

 each bearing laterad a more or less strongly defined darker dot. 



Arenivaga erratica Rehn 

 EE. Limbs shorter and stouter. Segments of abdomen normalh' immacu- 

 late Arenivaga apacha (Saussure) 



BB. Transverse clypeal swelling of face not as deep. Body thickly covered with 

 minute hairs; very much longer hairsalong the margin, particularly latero-caudad. 

 Cephalic femora with ventro-cephalic margin bearing a few stout, very short, 

 rather closely placed, knob-like spines proximad, succeeded in distal two-thirds 

 by a weakly arcuate row of very widely spaced, stout, very short, knob-like spines. 

 (Size medium small to small; form suborbicular. General color immaculate 

 reddish brown, hairs golden.) 

 C. Pronotum distinctly transverse. Hairy covering heavy. 



Eremoblatta subdiaphana (Scudder) 

 CC. Pronotum very weakly transverse. Hairy covering very heavy. 



Eremoblatta hirsuta new species 



The immature males approximate much more closely the adult 

 females, than they do adults of their own sex. This is shown by 

 the enlarged and much less specialized head, with eyes much re- 

 duced and well-defined ocelli absent (these indicated only by spots), 

 and by the pronotal and abdominal contour. 



The species found within the United States are all from the 

 Southwest, where they represent the only forms of the Blattidae 

 inhabiting the desert regions proper. Some species of Parco- 

 hlatta and Compsodes schwarzi, also occur in the Southwest, but 

 are confined in distribution to the desert and semi-desert mountain 

 areas, being rarely found out on the desert floor and then only as 

 migrants from their preferred environment. The exotic species 

 of the Polyphaginae are also, in large part, primarily desert in- 

 habitants. 



