NORTH AMERICAN COLEOPTERA. 29 



In my present studies I have been unable to follow the method pio- 

 posed by Erichson, of separating the species with and those without 

 frontal tubercles into separate groujxs. Unfortunately our species 

 are too variable. We have a certain number with well marked 

 frontal tubercles which are more pronounced in the males, while 

 males of other species have the tubercles as feeble as those of the 

 fenndes noted and their females may not be at all tuberculate. Tlie 

 present group is therefore the equivalent of groups I and L of mv 

 former paper (Trans. Am. Ent. Soc. 1870). 



In order that the species may be more readily handled and the 

 synoptic table rendered less unwieldly I proposed to divide the group 

 into the following series : 



Side margin of thorax explanate, usually a concavity near the hind angle. 



Series I-a 



Side margin of thorax not explanate 2. 



2. — Mesosternum distinctly carinate between tlie coxie. Thorax witliout liasal 

 line. Front tibise punctate on anterior face, the first tarsal joint longer 



than the second Series I-b 



Mesosternum not cai'inate. Anterior tibiae smooth in front 3. 



3. —Species entirely ferruginous, luteous or rufo-testaccous, never in any part 



black Series I-<* 



Species in great part piceous, head and thorax always black or piceous, 

 although at times with the sides pale. Elytra variable in color, either 

 black, dull red or yellow maculate Series l-rt 



The first two series might form fairly natural groups while the 

 other two are rather heterogeneous, but any attempt to further divide 

 them Avould result in more confusion than benefit. 



Series I-a. 



Front not at all or only feebly tuberculate. Side of thorax ex- 

 planate, the margin usually slightly reflexed, the basal marginal line 

 wanting or very fine. Anterior tibi?e smooth in front. Mesosternum 

 not carinate, except in explanatm. 



The species of this series are all moderately large and belong to 

 the region of our country west of the Missis.si])|)i River and east of 

 the Sierra Nevada Mountains. 



They may be distinguished in the following manner : 



Mesosternum distinctly carinate between the coxa? ; dypeus angulate eacli side 

 of the emargination ; thorax closely and equally punctured ; sides of 

 thorax and elytra dull red, the intervals i)unctulale...explaiiatus. 



MesosteriHini not carinate 2. 



