ODYNEIIUS. 271 



and truncate, but often appearing slightly bidentate. Thorax 

 widened before, retracted little or none. Post-scutel crenulate. 

 Metathorax very coarsely rugose; its concavity striate, but 

 cribrose in its superior moiety from the punctures which continue 

 with those of the superior face ; the latero-superior ridges blunted, 

 effaced; on each side a dentiform angle at the meeting of the 

 lateral and inferior ridges. First abdominal segment silky, 

 smooth, truncate, and a little rounded at the base ; the 2d short, 

 densely punctured; its posterior border offering a wide depressed 

 zone, widened in the middle, very coarsely cribrose, as well as 

 the following segments ; at times a little channelled, but the 

 border not turned up. 



Insect black. Mouth red, with a yellow spot at the base of 

 the mandibles; superior moiety of the clypeus yellow or red; 

 inner border of orbits and a spot behind each eye, red or yellow; 

 scape of the antennae red, with a black line above; a spot on the 

 front, yellow or red. Anterior border of prothorax yellow, often 

 followed with red; tegulss yellow or red, post-scutel and a spot 

 on each side of metathorax above, yellow ; segments 1-4 of the 

 abdomen regularly bordered with yellow; the first having its 

 border on each side widened or confounded with a spot or oblique 

 band, yellow surrounded with red, which leave above a black 

 trilobed or square notch ; often of red on each side or bordered 

 with yellow. Legs yellow, black at the base. Wings smoky or 

 a little reddened with a light violet reflection. 



Var. a. Clypeus red, with a yellow band on the summit. 



b. No red on 1st abdominal segment. 



c. Two yellow or red dots on the scutcllum (Tennessee). 



d. Prothorax red, bordered with yellow (Missouri). 



The crest of the post-scutel varies; sometimes finely crenulate 

 and continuous, sometimes dentate and notched in the middle. 



%. A little smaller. Clypeus polygonal, yellow, wider than 

 long, truncate on its anterior border, offering a very small tooth 

 on each extremity of this border; its apical margin a little pro- 

 longed, so that the polygon is not. regular, the inferior borders 

 forming thus a larger arc than the superior; hook o( the antenna 

 black or ferruginous; mandibles and ornaments oi' the head yel- 

 low or orange; a, red dot on the flanks before the teguhe ; often 

 the posterior border of the prothorax red and a little o\' red about 

 the scutelsj latero-superior borders of the concavity oi the 



