THE CANADIAN ENTOMOLOGIST. 



have passed through my hands, scarcely any variation occurring in many 

 individuals of all the species examined."* As far as I have been able to 

 observe, in series of individuals known to have been collected together in 

 one environment, there is comparatively little variability in sculpture, so 

 that radical departures in this respect are virtually sure signs of specific or 

 subspecific difference. 



The genus Omus may be divided into three quasi-subgeneric groups 

 of species, each distinguished by a remarkable peculiarity of habitus, as 

 follows : 



Pronotum without tactile setaa along the side margins. 



Elytra with very large and conspicuous foveae ; species stout and of 



large size. Northern coast regions Group I (Dejeani) 



Elytra with small and more or less inconspicuous fovese ; species 

 smaller, more abundant in the southern regions and disappearing 

 through smaller and more depauperate forms to the northward. 



Group II (Calijornicus) 

 Pronotum with numerous tactile setae along each side margin ; body sub- 

 metallic ; form rather slender and subcylindric ; foveae inconspicuous. 



Group III (snbmetallicus) 

 The Dejeani group, composed of Dejeani alone, is so well known 

 that it needs no further attention here ; and the submetallicns group, also 

 at present monotypic, is completely unknown outside of the Horn collec- 

 tion ; so my remarks are here limited to the Californicus group only. 

 This group is remarkably plastic, and consequently rich in species and 

 subspecies, as may be inferred from the following tabular statement : 



Species of the coast regions 2 



Species of the Sierras o 



*So the doctors disagree, as in the trite old saying-, and, in the dilemma thus 

 created, the average collector knows not which horn to seize. My own opinion 

 is that if Dr. W. Horn had exercised even slight acumen in dealing with his 

 . material, he would hive seen that nearly all the erratic variation in sculpture that 

 he announces is due to confusing and mingling together different taxonomic 

 units ; call these units what he may, they are constant and fixed forms, which 

 have developed in the numerous isolated valleys of the broken mountain regions 

 of California, or at different elevations, and it serves no useful purpose to refuse 

 to give them proper value, besides leading to needless complexity in nomencla- 

 ture. There is nothing gained by holding that what are commonly known as 

 subgenera or well-marked groups of species are the only real species, and then 

 stringing out from each numerous impossible categories of subsidiary forms. If 

 the binomial, and possibly even the trinomial, system is not to be lost in chaos, 

 we must descend from such an unphilosophically exalted idea of species. 



