162 AMERICAN COLEOPTERA. 



rather markedly in type from the other three by its more 

 depressed form, more widely separated eyes, stouter more 

 numerously dentate thighs, somewhat uneven elytral disk 

 and broader scutellum : 



Disk of prothorax with both median and dorso-lateral prominences ; 

 prevailing color brown ; thighs very stout, armed with four 

 acute teeth, decreasing in length posteriorly. (Middle States 



to Kansas and Texas.) mimus Say. 



Disk of prothorax without sublateral tuberculations ; hind thighs uni- 

 dentate ; prevailing colors black and white. 

 Eyes emarginate to middle, antennae less slender, outer joints sub- 

 quadrate or distinctly transverse. 

 Disk of prothorax more strongly tuberculate posteriorly than 

 anteriorly, legs bicolored, elytra tessellate. (Phoenix and 



Pinal Mountains, Arizona.') arizoneusis Schf. 



Disk of prothorax strongly gibbous in front, feebly tuberculate 

 posteriorly ; legs pale rufous, the tarsi dark ; elytra with 

 large median and apical black spots. (Arizona, Utah, Cali- 

 fornia.) gibbithorax Sch. 



Eyes very deeply emarginate ; antennas slender, all the joints longer 

 than wide ; prothoracic tuberosities subequal but feeble ; 

 legs black ; elytra with a conspicuous lateral median black 

 spot. Texas (Brownsville and San Diego). .texanus Schf. 



15. mimus Say. 



The large oval smooth space on the pygidium is character- 

 istic of the female rather than the male, as stated by Horn. 



Group III. 

 Three more or less dissimilar species, chinensis, qicadri- 

 maculahis and sordidzis, have constituted this, the third Group 

 in the Horn system, characterized by a single tooth on both 

 the inner and outer margins of the hind femur. In chinensis 

 {scutellaris Fab.) and quadrimaculatus the two teeth are of 

 about equal length, the outer one, however, being distinctly 

 stouter and more triangular. In sordidus the outer tooth is 

 always much shorter than the inner and often ill-defined. I 

 have, therefore, transferred it to Group V, with which it 

 agrees well in general habitus, and to which specimens 

 with undeveloped external tooth would naturally be referred. 

 In pruinhms of this group there is a more or less obvious 

 angulation of the outer margin of the femur which may be 



