NORTH AMKKICAN COLEOPTEHA. 209 



In addition to the above varieties it will be observed that those 

 with spotted elytra are sometimes pale beneath and often entirely 

 black. 



The tyi^ical canellus is similar to the variety quadriguttatus with 

 the addition of a dark suture and is consequently the equivalent of 

 histrio Lef. 



In all the forms specimens may occur with comjoaratively coarsely 

 punctured thorax or nearly smooth, with all intergrades. In the 

 black varieties the thorax is often alutaceous and subopaque. 



The above table is given merely as a means of accounting for all 

 the s|)ecific names which have appeared in literature and not as an 

 evidence of acquiescence in minute subspecific division. 



This species is widely distributed over the continent east of the 

 Rocky Mountains from Canada to Texas, extending thence west 

 through Arizona to Fort Yuma. 



METAt'HROMA Lee. 



The characters which will serve to distinguish this genus from any 

 other in our fauna are as follows: Thorax without post-ocular lobe, 

 eyes surrounded above and in front by a deep groove, middle and 

 posterior tibiae emarginate on the outer edge near the tip. 



Metackroma seems to be restricted to Boreal and Central America 

 with the exception of one species from Madagascar which probably 

 needs a new generic study. 



The species are not difficult in the cabinet, but the differences 

 which may be made known by description are not easy to be appre- 

 ciated. 



The first character used in the annexed table — the tooth on the 

 posterior femora — nnist be looked after with some care, as the tooth 

 is really very small, and could readily escape observation. The 

 thighs in the species with the tooth are generally stouter and more 

 abruptly narrowed at the knee than in those of the next series. 



Each elytron has eleven strite seven of which are between the 

 suture and the umbone, and two run parallel with the side margin. 

 Between the.se two series, that is, just exterior to the seventh, are two 

 short striic which begin posterior to the umbone from a common 

 point. For convenience in the following descriptions they are called 

 short strire. In some species these strife are distinct and regular, 

 while in others they are much confused or very irregular. 



The punctuation of the head and thorax affords useful characters. 



TBAN8. AM. ENT. SOC. XIX. (27) JULY, 1892. 



