NORTH AMERICAN COLEOPTERA. 71 



The following is the scheme : 



Lateral margiu of last ventral segment serrulate (3-171). 



Disc of thorax even, without fovese or callosities (1-25) Group I. 



Disc of thorax irregular, median line more or less sulcate, often with callosi- 

 ties (30-164). 

 Anterior tibife % arcuate and serrulate within ; clypeus acutely notched at 



middle, semi-circularly arcuate each side (30-34) Group II. 



Anterior tibise % arcuate and with a tooth near the tip (35-65).... Group III. 

 Anterior tibise % more or less arcuate, dilated at tip (66-172). 



Form depressed (66-145) Group IV. 



Form subcylindrical, slightly pubescent (150-169) ' Group V. 



Lateral margin of last ventral segment not serrulate, rarely interrupted (175 -246). 



Elytra acuminate at tip (173-193) Group VI. 



Elytra obtuse and serrulate at tip (198-244). 



Elytra with either costse or discal fovete, sometimes with l)oth (198-232). 



Group VII. 

 Elytra without cost» or discal fovese (237-244) Group VIII. 



The numbers in the tiible refer to the figures cm the accompanying 

 plates, the numbering being continuous for greater ease and ceilainty 

 of reference. Regarding the figures on the plates it must be remem- 

 bered that while many of the species are practically constant in 

 sculpture, others are greatly variable. Every figure represents the 

 sculpture of the specimen in hand at the time, that one being chosen 

 which seemed most closely to represent the average sculpture. 



Group I. 



In this group we now have six species, two of these were so placed 

 by Dr. LeConte, and I have added four others, three being for the 

 first time here described, Avhile the other had been placed in the series 

 with the disc of thorax unequal. Five of them agree in having the 

 thorax gradually narrowed to base, very feebly so in purpureovittata. 

 In Edirardsii, howevei', the thorax is broader at base and the sides 

 irregular. All agree in having the prosternum lobed in front, very 

 feebly in the larger species and quite prominently in the smaller 

 forms. 



The following table will assist in separating the species : 



Larger species ; the elytral costfe very distinctly elevated ; prosternal lobe rela- 

 tively feeble ; ventral segments with distinct lateral callosities. 

 Clypeus broadly emarginate. 



Middle and posterior femora % and 9 coarsely serrate on their posterior 



edges 1. atabalipa. 



Middle a^id posterior femora simple 2. octocola. 



Clypeus semi-circularly emarginate and with a tooth each side. 



3. EdwaiHlsii. 



