[5] NORTH AMERICAN COLEOPTERA. 161 



the disk are very abrupt and more or less distinctly limited 

 by a line, as in many species of Ljemophloeus, they are des- 

 ignated as the pleurce, the word eplpleurce being applied to 

 the second portion of the inflexed sides above mentioned, 

 and the word Jiypopleurce to the first, or raised lower margin. 

 This last has been called the epi pleural fold by Pascoe; but 

 in addition to the undesirability of two words to express 

 our meaning where one can just as well be employed, we 

 must consider the fact, admitted by the distinguished au- 

 thor quoted, that the hypopleurae are not in reality folds at 

 all. In a few of my previous descriptions I have used the 

 word hypopleurre to designate the entire inflexed sides or 

 hypomera, but in future the names here given will be ad- 

 hered to. 



While dealing with kindred topics, it seems desirable to 

 indicate the perversity of the brain in interpreting the ima- 

 ges formed upon the retina of the eye in delineating and de- 

 scribing form. A good way to illustrate this is to observe 

 the letter S in print, where the two salient curves in the or- 

 dinary position of the letter appear to be of nearly equal 

 size; if now the letter be inverted, it will be seen at a glance 

 that the lower portion in its former position is much the 

 larger. In a similar way vertical lines appear relatively 

 longer than transverse lines, and this has led to many errors 

 in describing the shape of the prothorax; when the width 

 and length of the latter are equal, it invariably appears at 

 the first glance to be longer than wide, and is generally so 

 described, thus introducing an element of confusion and 

 doubt for those attempting to identify species from descrip- 

 tions. This defect can be gradually overcome in various 

 ways, but perhaps best by trying to delineate the form of 

 the insect; for those who have never attempted it, this will 

 generally be found a very difficult feat, and one requiring 

 several attempts before a satisfactory outline can be pro- 

 duced. 



The short diagnoses usually given are purposely omitted, 



