198 PAPEES BY DK. B. CLEMENS. 



ing. If, on the contrary, the wings of the insect are fissured, 

 it will be found under the second principal category, printed 

 in the same kind of type f as the first, viz. : those whose 

 " wings are penniform or fissured." 



If the specimen belongs to the first category, the student 

 will notice whether the hind-wings are supplied with a 

 " bristle," or not ; if it is absent, the specimen belongs to a 

 family included under the second category. He will then 

 observe whether the wing structure in both the fore and hind- 

 wings is alike ; if it is, and the specific diagnosis below this 

 category corresponds to his specimen, it belongs to the family 



If the wing structure is not alike in the fore and hind- 

 wings of the specimen, then its family must be sought under 

 the category marked**. If this has not a " costal vein" in the 

 hind-wings, it is included in the division marked ; but if it 

 has a " costal vein," then under the next affirmative category 

 referring to the same structure. This latter category is again 

 subdivided into two others, insects " With an intercostal cell" 

 and " Without an intercostal cell" and the latter is again 

 subdivided into groups according to the peculiarities of the 

 (f internal vein" 



The specimen, however, probably is supplied with a 

 " bristle" at the base of the costa of the hind-wings, and in 

 this case the student will pass, without further examination 

 of the categories included in the second one, to the corre- 

 sponding affirmative category, printed in the same kind of 

 typef as the second, viz. : insects " with a bristle at the base 

 of the hind-wings." 



If the wings are " without long cilia," the specimen will 

 be found under the next head; but if, on the contrary, the 

 wings have " long cilia," all the matter included under the 

 negative category may be passed over until the corresponding 



f In the original, Dr. Clemens has endeavoured to introduce a great variety 

 of types, so as really to carry out this idea, but this, in reprinting, I have found 

 impracticable. H. T. S. 



