NORTH AMERICAN COLEOPTERA. 17 



Notes on the species of Ol'HTHEBIlTS of Boreal Aiiiei-iea. 



BY GEORGE H. HORN, M. D. 



Our species of this genus have been described by Dr. LeConte 

 with the single exception of Holmbergi, a type of which is in the 

 collection at Cambridge. At the time of his i-eview of the genus all 

 my material was placed at his disposal and some of the tyi)es or 

 duplicate types are now in my collection, so that all the species with 

 one exception are now in my possession. 



As the species ai'e all of rather small size it is not an easy matter 

 to describe the thoracic form and sculpture in such a manner as to 

 make the differences easily appreciated. It has, thei-efore, seemed 

 profitable to prepare sketches of them, so that with the aid of the 

 descriptions the various species may be determined by those who 

 possess them, without the necessity for refei'ence to standai'd series. 



Since the publication of the table of our species by Dr. LeConte 

 (Proc. Amer. Philos. Soc. 1878, p, 378) an important review of the 

 European species has appeared from Mr. A. Kuwert (Deutsche 

 Zeitschr. 1887, p. 369). In this essay the seventy-eight species are 

 divided into sixteen subgenera. 



In a study of our species in a comparison with those of Europe 

 it is possible, by allowing a little latitude to the subgenera, to admit 

 certain of our species, while a number might warrant the formation 

 of other subdivisions, but it seems to me unnecessary to burden our 

 nomenclature with names for generic groups which have not full 

 generic value. 



The form and sculpture of the thorax give the readiest method of 

 separating the species ; these are supplemented by elytral differences 

 which are neither so well marked nor constant. In all the species 

 the thorax is narrowed at base, sometimes gradually with a slight 

 sinuation as in lineatus, or with a deep, more or less abrupt sinuation, 

 as in discretus. In every case there is a transparent side-margin ex- 

 tending sometimes from the apical angle to base, or merely from the 

 beginning of the sinuation to base. In one species, benefossus, the 

 border is extremely narrow and within the emargination. As a rule 



TKANS. AM. ENT. SOC. XVII. (3) JANUARY, 1890. 



