NORTH AMERICAN COLEOPTERA, 289 



survival of the Ijiiear impressions of Helopliorus, and are homolo- 

 gous with similar impressions, to which attention has been called in 

 Philydrus et at. 



There is considerable variation in color in nearly all the species, 

 and to an extent which renders it troublesome to distinguish some 

 of them without close reference to the structural characters, which 

 are fortunately well marked, enabling groups to be formed. 



In glancing over the list of species it will be a matter of surprise 

 to many that so few of the forms are peculiar to our fauna. It may 

 also be questionable how many of those common to our fauna and 

 Europe have been introduced by means of commerce. 



In studying Bedel's recent work (Faune du Bassin de la Seine) a 

 large number of the species are noted as extending their habitat from 

 temperate Euroj^e through the north of Asia and in some instances to 

 Japan. Every one of these has been found on our continent, and a 

 certain number of other well-known European species having oc- 

 curred leads to the inference that they should also be found in Siberia 

 (granarius, tridis, depressm). 



It seems to me that but a small number of the species owe their 

 presence in our fauna to introduction by human agency. They ap- 

 pear to be rather members of a circum-polar fauna equally native 

 in either hemisphere, distributed at a time when continental division 

 was less abrupt than in the present geologic era. Many of the spe- 

 cies c(jiinect directly with the northwestern regions as indicated 

 above, while others seem restricted to the Atlantic ; these latter, if 

 any, are the truly introduced specks (melanoeephalus, pygm(ev.s,\ii- 

 griceps, hceviorrhoidalis). On the other hand it seems probable some 

 of our Pacific coast species (luniger, fivibriatus, fulvipemiis, adimi- 

 bratus) occur likewise on the eastern Asiatic coast. In fact, several 

 Japanese species look very like the first two named. 



The species at present known to me have been arranged in ac- 

 cordance with the annexed table. 



Anterior tibise emarginate on the outer edge near the apex, a conspicuous spur 

 below the notch (PI. ix, fig. 17). 

 Sides of thorax slightl.y sinuate posteriorly; form subdepressed...littoralis. 

 Anterior tibise not emarginate (PI. ix, fig. 16). 



Sides of thorax distinctly sinuate posteriorly; maritime species •) 



Sides of thorax regularly arcuate and narrowed from base to apex. ~ 



Elytral intervals flat or slightly convex ; species glabrous 3 



Elytral intervals alternately subcostiform at apex; surface sparsely pubes- 

 cent. 



14. 



TEANS. AM. ENT. SOC. XVII. (37) 



SEPTEMBER, 1890. 



