NORTH AMERICAN COLEOPTERA. l'^'^ 



author counted in the puncture at the apical margin, which 1 think 

 Fauvel lias clearly shown to belong to the marginal scries, and has no part 

 in the discnl series yiroper. This difference of notation n.ust always be 

 borne in mind, as nearly all the species described in our fauna smcc 

 Erichson's work follow his notation. 



The sexual characters of the male, independently of the ddate.l tars,, 

 are in nearly all the species very well marked, the terminal ventral seg- 

 ment beino- always more or less emarginate. The different modifacations 

 of the ema'rgination afford excellent and very certain means for separating 

 species whidi superficially resemble each other very closely. 



The following is the scheme of sub-division adopted in the present 



essay : 



Thorax with a distinct and regular series of dorsal punctures. 



Anterior tarsi more or less dilated. ^ ^^^ ^ 



Dorsal series of three punctures Skkiks B* 



Dorsal series of four punctures J""'- * 



Dorsal series of five punctures 



Anterior tarsi filiform in both sexes. 



Dorsal series regular, but varying in number ........bK.ni.s w. 



Thorax irregularly punctured, no distinct dorsal series. Anter.or tars, d.atecL 



It is well known to those who have studied the genus that there is often 

 •in individual variation in the number of the dorsal punctures, usually by 

 •tn increase, that is, a tripunctate species may become quadripunctate 

 hut I have observed that the adventitious puncture is usually out ot 

 line and in my experience has never occurred on both sides at the same 

 time, so that a species 5-punctate on one side and 4-punctate on the other 

 wil be found to be really a 4-punctate species. 



The method of sub-division adopted by Fauvel (Faune Gallo-llhenane) 

 based on the form of the head, is not applicable to our species, and is 

 probably as illusory for those of Europe. 



A. 



The essential characters of this series are-anterior tarsi dilated, dorsal 

 scries of thoracic punctures three. 



The anterior tarsi are usuall more widely dilated in the male than in 

 the female, but species have been observed in which the differences m 

 this respect are very slight. The dilatation is usually moderate, rarely 

 broad, and never patellate as in some of the next series. The males have 

 in all the species a well-marked emargination of the last ventral segment, 

 varying somewhat in degree. 



