30 ]Mr. D. Slmi'p's Cunti'ibutlons to the 



proved as yet unattainable, and tliis must, in my opinion, 

 continue to be tlie case imtil all or nearly all the actually 

 existing species are known to us, and until descriptive 

 terms arc used Avitli much more precision and definition 

 than is at present the case. Hence it happens that a large 

 part of the time of" those occupied with dcsci'iptive ento- 

 mology is spent in trying to ascertain the value of the 

 names used by their ])redecessors; and it by no means un- 

 frequently happens that the efibrts of those predecessors 

 have considerably increased instead of diminishing the 

 work to be accomplished by their successoi'S. The prac- 

 tical result of these difficulties is, that an increasing im- 

 ])ortauce is attached to type specimens. This, in my 

 opinion, is a perfectly natural and satisfactory result. 

 Science teaches us to deal with facts as directly as 

 possible, and the actual specimens described by an author 

 afford a coitaiuty as to the species he intended which can 

 be attainable by no other method. 



The permanent preservation of valuable and fragile 

 specimens and the associating of them in an inalienable 

 manner with the name given to them, is, however, no easy 

 task. But, in order to accomplish it in the case of the 

 fragile insects here described, I have devised a method 

 of covering and hermetically sealing the ty])e specimens, 

 which will, I ])elieve, accomplish their complete protection 

 from all destroying agencies except fire and rude physical 

 catastrophes. Kearly all the smaller species here de- 

 scribed, as well as a considerable proportion of the larger 

 species, I have preserved by this method ; ami, rendered 

 bold by the valuable results it promises, I have ventured 

 to describe even minute sjiecies where 1 had but a single 

 exami^le of it from which to draw up my description. I 

 have taken some steps to test the efficacy of this mode 

 of preservation, and hope soon to be able to publish a 

 descrI})tion of the method. 



As regards the terms " South America " and " tropical 

 America," constantly used in this pa])er, I should ex))lain 

 that 1 mean all the ])arts of the ^'ew A\'()r1d south of the 

 United States of 2Surlh ^Vmerlca, incliuling the ^^'est 

 India Islands, but excluding Chili and I'atagojiia. The 

 fauna of Chili is known to be very different from that of 

 the counti-ies on the eastern side of the Andes, and of the 

 JS'tujj/ii/liHi(l(e of l*atagonIa i know absolutely nothing. 



The 487 species here enumerated are divided among 



