REVISION OF ELEODIINI BLAISDELL. 235 



Thorax subquadi-ate, sides not strongly rounded; elytra smooth, not at 

 all mnricately punctate. 



Elytral striae rather closely placed gracilis. 



Elytral striae distant var. distans. 



Thorax snbcylindrical, sides evenly and feebly arcnate throughout ; 

 elytra with unimpressed distant rows of nearly simple punctures. 



suJjcyUndrica. 

 Thorax not constricted at base ; males more or less caudate. 



Elytra strongly ventricose; apical angles of prothorax moderately 

 prominent anteriorly; first joint of the pro tarsi (male) clothed at 

 apex beneath with a transverse tuft of golden modified spiuules. 



rcnfricnsa. 

 Elytra feebly ventricose; apical angles of prothorax larger, more prom- 

 inent anteriorly, acute and more or less reflexed ; first joint of ante- 

 rior tarsi without transverse tuft of spinules var. falli. 



Elytra rarely ever ventricose and distinctly striato-punctate. 



Apical angles of prothorax feeble and not prominent anteriorly. 



eschscholtzii. 

 Apical angles usually well developed, acute and anteriorly prom- 

 inent var. Iiica: 



Elytra not distinctly striato-punctate and elongate oval. 



Apical angles of prothorax everted tcniiipcs. 



Apical angles not everted loickhami. 



The student must bear in mind that in all in'obability he will find 

 the above table inadequate as an aid in the determination of all 

 specimens. If the examples be more or less typical there should be 

 no trouble, but among sjDecies so polymorphous, puzzling forms will 

 constantly be found. 



In the text I have given attention to the most marked incipient 

 races as well as to uniques and aberrations when at hand. 



Genealocjij. — To speculate upon lines of descent of the species con- 

 stituting the present Section involves great doubt as to the correctness 

 of the assumptions^ but may be a useful working hypothesis. Never- 

 theless I must present my convictions; for there is no doubt in my 

 mind but that the ancestral stock had the femora strongly armed as 

 in armata., and that this species is a direct and somewhat modified 

 modern exponent of that stock. 



A typical armata does not have the sides of the prothorax sinuate 

 or constricted before the base. Now, I have before me examples of 

 armata which have the sides of the prothorax as strongly sinuate as 

 in any dentipes^ and all of the femora are well armed. 



I advance the theory that all of the species now constituting the 

 present section of the Dentipes Group in our fauna — which includes 

 Low^er California as well as all of that territory north of Mexico — 

 have had their origin from the ancestral armata stock. It may be 

 asked when did this divergence take place? I would answer, first, 

 that which took place in early times, and, second, that which has 

 taken place in more recent times. 



