60 Bulletin of the Brooklyn Entomological Society Vol. XVI 



STANDARDIZED DESCRIPTIONS. 



Entomology naturally depends for its progress, particularly on 

 its taxonomic side, on accurateness of observation and keenness 

 of discrimination. The small size of insects in general and par- 

 ticularly of their structures, has compelled the use of magnifiers 

 in order to see. As time has advanced, lenses simple and com- 

 pound have improved in quality in many ways, and discrimina- 

 tory characters in insects have in consequence become more and 

 more minute and subtle. The natural result has been that our 

 categories are more sharply and clearly differentiated, with a 

 consequent redefining and splitting up of old genera and even of 

 species. The limit of application of a hand magnifier is reached 

 at X 40. Beyond that, the compound microscope must be used, 

 with its highly enhanced power and the limitations that go with 

 that power and with working in one plane. 



The advent of the binocular microscope with erecting prisms 

 has ushered in a new period. New values are perceived and subtle 

 distinctions are appreciable through this instrument of precision. 

 But the extreme accuracy that comes with practicable working 

 magnifications up to X 75, permits a proper examination and 

 appreciation of taxonomic characters. Added to this, the stereo- 

 scopic effect of the binocular brings out the true relation of 

 structures to the insect and to each other. 



Here, with these high magnifications available, we come to the 

 peril of too fine differentiations, leading to species founded on 

 evanescent or too subtle characters. Far more important, they 

 reveal things beyond the potency of the hand lens, and far more 

 accurately, leading to finding valid though minute and heretofore 

 unsuspected characters. Whence, a description under a magni- 

 fication of over X 40 under the binocular will contain things in- 

 visible under the ordinary hand lens, and make such a description 

 useless to the worker without a binocular; or lead him to a 

 synonym because of the invisibility of these characters, and there- 

 fore absence, to him. 



It might seem that in all future complete descriptions, two 

 things should be definitely and precisely stated — the first, the 



