350 PROCEEDINGS OF THE NATIONAL MUSEUM tol. ne 



14. Pygidium with sides diverging slightly apically and convex on the apical 



end niorata Cresson 



(also vicina Cresson) ^ 



Pygidium with sides converging slightly and the apical end slightly 



concave 15 



15. Bands of yellow on the tcrga with little or no emargination. 



frontata frontata Say 

 Bands on the terga deeply emarginate anteriorly . . frontata rani Rohwer 



16. Band on tergum 2 distinctly wider than the bands on other terga . . 17 

 Bands on all terga subequal 19 



17. Small species, approximately 8 mm. in length nitida Banks 



Medium in length, 10 to 12 mm 18 



18. Band on tergum 2 deeply emarginate .... clypeata prominens Banks 



(probablj- also halone Banks) 

 Band on tergum 2 not emarginate or, if so, very little. 



clypeata clypeata Dahlbom 

 (probably also clypeata gnarina Banks, dakotensis Banks, posticata 

 Banks,* atraviontensis Banks, rhois Rohwer*) 



19. Small species about 9 mm. in length; clypeal denticles reduced to two 



(Northeastern United States) astarte Banks 



Medium to large species, 10 mm. or longer ; tlu-ee more or less distinct clypeal 

 denticles 20 



20. Denticles on the clypeal margin separated bj^ a distance subequal to one- 



fifth the width of the medial lobe; a distinct transverse ridge just above 



the denticles (Eastern States) deserta Say 



Denticles on the clypeal margin in approximate conjunction; no transverse 

 ridge on the surface of the medial lobe 21 



21. Markings yellow 22 



Markings white to cream 26 



22. Lateral clypeal denticle prominent; the medial clypeal denticle greatly 



reduced or absent 23 



Three clypeal denticles subequal 24 



23. Medial clypeal lobe with a distinct transverse swelling about the level of the 



anterior tentorial pits (Central States south to Texas). 



occipitomaculata Packard 



Medial clypeal lobe ^vithout a distinct transverse swelling but generally 



convex nigrescens arelate Banks 



24. Length about 10 mm.; denticles on the clypeal border very indistinct (Cali- 



fornia and adjoining states) nigrescens munda Mickel 



(probably also aequalis aequalis Provancher, varians Mickel, dentifrons 

 Cresson) 

 Length about 13 mm. ; denticles on clypeal border more distinct 25 



25. Seventh tergum with yellow to the sides of the pygidium (West Coast 



States) tepaneca Saussure 



Seventh tergum immaculate (Central Plains States) sexta Say 



(also posticata Banks, rhois Rohwer) 



* The males of morata Cresson and vicina Cresson so far are inseparable except 

 by association with the females. 



* The type of posticata Banks runs to couplet 18b. It is a unique that may be 

 sexta Say with an abnormally wide band on tergum 2. The type of rhois Rohwer, 

 which also runs to this couplet, could be the male of clypeata gnarina Banks, but 

 the type locality is out of the known range of that species. 



