NORTH OF MEXICO. 



381 



ruficolle. 



r xi fi c o r n e 

 fl a v i p e s -. 



Head neither tuberculate nor horned. 

 Thorax rufous, elytra black. 

 Thorax and elytra black. 

 Surface opaque. 



Elytra without red spots. 

 Antennae pale. 



Antennee black, three basal joints pale. 

 Antenna- black, three basal pale, terminal ferru- 

 ginous, j a n u s . 

 Elytra with 'an oblique red spot on each. elliptic um. 

 Surface shining black. 



Presternum horizontal, apex prominent. 



Head with distinct transverse groove and frontal 

 impression. 

 Frontal impression rather deep ; species broader, o r e g o n ensc. 

 Frontal impression faint; species less rounded, amcricanum. 

 Head without transverse impression. 



Thorax very sparsely punctured; surface less 



shining. 1 a e v i p e s . 



Thorax densely punctured ; species small, 



shining, black. 



m i c a n s 



Prosternum convex between the coxae ; apex deflexed 

 and obtuse. 

 Smaller species, black, with an seneous tinge, picilabrum. 



more elongate. 

 Larger species, black, more broadly oval. s u b c o s t a t u m . 



P. excavation, Say, (Diaperls) Joum. Acad. 8, 207. 



A very abundant species over the entire district East of the Rocky Mountains; easily 

 recognisable by the black color, shining surface and corniculate head. Specimens occur 

 in the Western States of rather more elongate form and less deeply striate elytra. 



Length .18-.21 inch. 



P. oyanescens, Lap. et Iimllc, Ann. 8c. Nat. XXIII, i>. 350. 



Differs from the preceding, in its more elongate form, less rounded sides and by its 

 blue color. 



Length .18 inch. 



Occurs in the Gulf States. 



AMBRI. PII1LOSO. SOC VOL. XIV. — 96 



