NORTH AMERICAN COLEOPTERA. 255 



It will be observed in all our species that the genjB are coarsely 

 and closely punctate without any exception ; for this reason no men- 

 tion will be made in the separate descriptions. 



In the greatest number of species the thorax has regularly arcuate 

 sides, converging to the apex, but in a small number the anterior 

 angles are obliquely truncate with a post-apical angulation, and in 

 two of these species the thorax is not narrowed in front. In the 

 former series the antennte, with very few exceptions, have the outer 

 joints piceous, while in those with the angles truncate the antenniB 

 are entirely pale, or in no case decidedly piceous externally. 



On comparison of our species with th(jse of Europe it will be seen 

 that the number of species in which the elytral strife have confused 

 punctuation is more than twice as great as those with regular striae, 

 wiiile in our fauna only three of the twenty -three have irregular 

 strise. In number, as many s|)ecies are known in our fauna as in 

 Europe, including Plectroscelis and Chaetocnema under the one name. 

 It is therefore hardly ])robable that our species will be greatly in- 

 creased by future collections. 



In the accompanying table it has been found necessary to modify 

 the arrangement given by Dr. LeConte (Proc Am. Philos. Soc. 

 1878, p. 419) and to remove species from the series with smooth 

 head to the punctate series. By some accident or oversight two of 

 Melsheiraer's species had been omitted, but have been studied from 

 the types now in the Museum of Comparative Zoology at CJambridge. 

 My thanks are due to Dr. Hagen for his kind assistance in their 

 discovery. 



The following table will assist in the identification of the species, 

 but care must be used in the determination of single examples: 



Sides of thorax regularly arcuate from base to apex, without oblique truncation 



at the front angles 2. 



Sides of thorax obliquely truncate at the front angles, with a ])ost-apical angu- 

 lation 13. 



2. — Head punctate, .sometimes indistinctly 3. 



Head absolutely impunctate 10. 



3. — Punctures of elytral strife confused or irregular, at base 4. 



Punctures of elytra in regular strife 5. 



4. — Strise 1-4 or beyond much confused as far as the middle or even beyond. 



The outer two strife only regular, the confused punctures of disc extend- 

 ing beyond the middle 1. cribrata."^ 



The outer three or four strife regular, the confused punctures of disc ex- 

 tending barely to middle ; sides of elytra opaque 2. pertiirbata. 



Strife 1-2 or 1-3 irregular, near the base only ; punctures of thorax coarse. 



Form regularly oval 3. iri*e$>;iilaris. 



Form elongate, subcylindrical 4. siibcyliiidrica 



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