NORTH AMERICAN COLEOPTERA. 



Subgen. Aphodius Auct. 



Scutelluni small, not more than an eighth or a tenth the length of 

 the elytral suture. 



This character is about the only one Avhich can be used to distin- 

 guish the mass of species which follows from the comi)aratively few 

 which precede. Various attempts have been made to divide the 

 series, and about a dozen names have been proposed by Mulsant and 

 Motschulsky for sections of variable extent, but the characters have 

 been found to possess very little value and to have such a shadowy 

 foundation that most recent authors have abandoned them entirely. 

 They are, however, divisible by characters sometimes very sharply 

 defined and nearly as often evanescent, into groups which vary in 

 the number of species they contain. The greatest difficulty is in 

 determining to what extent division should be carried. 



As subdivision by synoptic tables is intended to assist in the de- 

 termination of species and not to enable the author to illustrate his 

 ideas of the intricate relationships of the groups or species among 

 themselves, the simpler and shorter the primary tables are made the 

 more nearly do they serve the purpose of their publication. It has 

 seemed to me at all times better to discuss synthetic nuitter.s entirely 

 apart from the tables. The object should be to enable the student- 

 reader to determine the species with all possible facility and accuracy, 

 this accomplished he will be enabled to follow intelligently any dis- 

 cussion. Progress in Natural History necessarily starts from a basis 

 of species, and until these are accurately described so that others can 

 arrive at a knowledge of them no great advance is possible. 



In the endeavor to tiuhdWide Aphod Iks proper I have followed the 

 plan of Erichson (Insect. Deutschl. vol. iii) with modifications to 

 suit the evidently more heterogeneous material of our fauna. The 

 suggestion of groups for species which have no equivalents in the 

 European fauna is necessary, and will be understood, but among the 

 species fimbriate with unequal spinules I have been conq)elle(l to 

 ignore one of Erichson's main subdivisions based on the tidierculate 

 or simple head, from the fact that among our species the character 

 is evanescent. 



There are other difficulties with this method of subdivision, a.< 

 there will be with any that can be i)roposed, which will be alluded 

 to in their proper places. 



