120 BULLETIN 63, UNITED STATES NATIONAL MUSEUM. 



from al)ove and strongly declivous in the former, much more atten- 

 uated and pointed, and gradually declivous posteriorly in the latter; 

 anterior femora mutic in the former, armed in the latter. 



Cognuta Haldeman is a form of extricata^ and the males have the 

 anterior femora armed and therefore distinct from arcuata. 



The large series of some 400 examples of extrlcata warrant me in 

 drawing the above conclusions. Upon the form of the elytra alone 

 I woidd not separate arcuata^ but as far as I have been able to com- 

 pare males of the two species, those of arcuata are never armed. 



It is possible — as in annata — that extricata may lose the femoral 

 teeth in certain examples, and arcuata to gain them ; it is either sup- 

 pression in the one or atavistic reversion in the other. If it be found 

 a common occurrence there would still be sufficient characters to dif- 

 ferentiate arcuata; the latter might be considered out of place in the 

 present subgenus. 



The mentum is more or less parabolic in outline and rather more 

 than moderate size ; the lateral lobes are small and not usuall)^ notice- 

 able ; surface longitudinally subcarinate at middle and deeply foveate 

 laterally, scabrous and feebly setigerous. 



The prosternmn is not suddenly protuberant ventrally with the 

 coxae, but moderately so and more or less evenly arcuate from the 

 anterior border ; the intercoxal portion is subhorizontal or moderately 

 arcuate, gradually narrowed behind and quite strongly mucronate. 



The mesosternum is more or less arcuately declivous and concave. 



The metasternum laterally between the coxa^ is as long as the width 

 of a mesotibia at apex. 



The abdominal process is feebly transverse (male) or more strongly 

 so (female), and one-fifth (male) to one-third of its own width wider 

 than the metasternal salient. 



The post-coxal part of the first ventral segment is equal in length 

 to the third; the second is about twice as long (male) or distinctly 

 twice as long (female) as the fourth. 



The profemora are moderately clavate, the mesofemora just the 

 least thickened outwardly; the metafemora are subequal in width 

 throughout. 



The tibial grooves are shallow, the margins not strong. 



The tibia* are without distinct tarsal grooves, which are at times 

 feebly indicated. Articular cavities closed. Tarsi moderate. Pro- 

 tarsi stouter in the female. 



Tarsal formula 



Female.— 2 2J 3 4t 



Pro. Mc'so. Meta. Metatibia. 



Male.— 2 23 3 5 



