THE TUMBLING FLOWER BEETLES. 1317 



2430 (779G). MORDELLTSTENA ARIDA Lee., Proc. I'hil. Acad. Nat. Sci., XIV. 

 1862, 48. 



Larger and slightly darker than lute a. Ridges of tibue and tarsi longer 

 and stronger than there, those of the first joint of hind tarsi much more 

 oblique. Length 3.5-4 mm. 



Lake, Porter and Tippecanoe counties; scarce. June 27-July 

 21. The specimens from Lake and Porter counties were taken from 

 the flowers of the prickly pear cactus, Opnntia rafincsquii Engelm. 

 Both LeConte and Smith state that 

 at'ida has but two ridges on first joint, 

 but all the specimens at hand have three. 

 Dr. Smith pronounces them arlda, stat- 

 ing that "the difference in the ridges is 

 within the range of variation." This is, 

 of course true, but how about the keys, 

 which are based on an unvarying num- 

 ber of ridges? 



GROUP C. 



Fig. 577. a, Hind tibia and tarsus of 



In this group the tibia3 bear tWO Mordeliustcnatrifanciata; b, elytron of same; 

 , ,. f, elytron of M. limbalis. (After Smith.) 



equal oblique parallel ridges on the 



outer face. (Fig. 577, a.) The following species have been taken 



or should occur in Indiana : 



KEY TO INDIANA SPECIES OF GROUP C. 



(/. First joint of hind tarsi with two oblique ridges. 



b. Second joint of hind tarsi with but one oblique ridge. 



c. Elytra black with two transverse yellow bands, the front one part- 

 ly interrupted at suture by a prolongation of the black band at 

 base. 



(1. Body black ; thorax black with basal margin and sides dull yel- 

 low. 2437. TRIFASCIATA. 



(hi. Body yellow; thorax yellow with a faint fuscous cloud on disk. 



2438. LEPIDfLA. 



cc. Elytra without transverse yellow bands. 

 e. Color above wholly or in great part pale. 



f. Thorax with front angles and a large spot on center of disk 

 black. i>430. UMUALIS. 



//. Thorax and elytra wholly pale clay yellow. 2440. VAPIDA. 



ee. Color above wholly or in great part black or piceous. 

 //. Elytra with a reddish-yellow oval humeral spot. 



2441. BIPLAGTATA. 



</!/. Elytra without distinct humeral spot. 



//. Head, thorax and legs, except the hind femora, reddish-yel- 

 low. DIM i i AT A. 



