NORTH AMERICAN COLEOPTERA. 87 



In several species, owing probably to the small number of specimens, 

 it is not possible to assert with certainty that they have the fourth ven- 

 tral lobed in the male. They have, however, the seventh ventral simple, 

 the third and fourth foveate or plicate, and by inference they too are like 

 the others of the series to which they belong. 



In one species {prospiciens) it will be observed that the seventh ven- 

 tral of the m'ale is broadly triangularly emarginate and the fourth ventral 

 lobed. We have thus the chief characters defining two groups united in 

 one species. 



In all the species there will be observed on the side of the head behind 

 the eyes a fovea in and around which the punctures are denser. Those 

 species with the head decidedly narrower behind the eyes have but little 

 trace of the fovea. 



In order that the various sexual differences above recorded may be 



more accurately described, and the species better defined, it is proposed to 



divide our species into three series, as follows : 



Last ventral segment % simple Series A. 



Last ventral segment % emarginate or incised. 



Fourth ventral segment 'J, lobed Series B. 



Fourth ventral segment % simple Series f. 



Series A. 



The essential character of this series consists in the simple terminal S 

 ventral segment. It is also to be observed that the fully developed males 

 have the fourth segment prolonged in a lobe variable in width and length 

 not only between difierent species but also between males of the same 

 species. All the males have either a puncture or short transverse plica 

 at the middle of both the third and fourth segments. The females have 

 usually an entirely simple venter, four species only as far as known to me 

 have a plica on the third segment alone. 



In consequence of the variability of the males I have thought it ad- 

 visable to describe the forms separately, and I have accordingly impro- 

 vised three terms to indicate them : 



Complete form is that in which the lobe of the fourth ventral is fully 

 developed. 



Incomplete form that in which the lobe is abbreviated. 



Imperfect form that in which the fourth segment is truncate posteriorly 

 without trace of lobe. 



Of these three forms the most abundant is the complete form, nearly 

 as numerous are the imperfect males, while the incomplete males are far 

 less common. 



