102 R. W. Dawson 



SYNOPSIS OF THE SPECIES 



1. Posterior margin of pronotum depressed below the level of the 

 adjacent surface 7 



Posterior margin of pronotum not depressed 2 



2. Hind angles of pronotum distinctly, usually rather strongly im- 

 pressed 6 



Hind angles of pronotum feebly or not at all impressed 3 



3. Pronotum viewed from above very distinctly wider just behind 

 the middle than at the base, the side margins very strongly 



arcuate subangulata calif ornica 



Pronotum viewed from above but little if any wider near the 

 middle than at the base, the side margins much less strongly 

 arcuate 4 



4. Size smaller, 6-10 mm. in length; western species 5 



Size larger, 10-14 mm. in length; eastern species tristis 



5. Clypeal margin rounded, feebly or just perceptibly emarginate 



at the middle; length 6-8 mm carhonata 



Clypeal margin subtruncate, moderately emarginate at the mid- 

 dle; length 8-10 mm tenebrosa 



6. Anterior angles of pronotum obtuse, distinctly impressed, color 

 averaging darker, rufo-testaceous to nearly black obscura 



Anterior angles of pronotum acute, feebly impressed, color 

 lighter, rufo-testaceous hayde7ii 



1. Depressed basal zone of pronotum relatively wide and complete 

 from side to side 8 



Depressed basal zone of pronotum much narrower, nearly or 

 quite obsolete at the middle frondicola 



8. Clypeal margin almost evenly accurate from side to side, less 

 strongly reflexed; head relatively wider harperi 



Clypeal margin subtruncate, often slightly emarginate at the 

 middle, more strongly reflexed; head relatively narrower basalis 



Diplotaxis tenebrosa Fall. 



1909. Diplotaxis tenebrosa Fall, Trans. Amer. Ent. Soc, xxxv, pp. 

 13, 35-36. 



208 



