oO JMr. ]). Sharp's Contributions to the 



pi'oved as yet unattainable, and tliis must, in my o])inion, 

 continue to be tlic case imtil all or ncai-ly all the actually 

 existing species are known to us, and until descriptive 

 terms are used -with much more precision and definition 

 than is at present the case, llence it happens that a large 

 part of the time of those occupied with descriptive ento- 

 mology is spent in trying to ascertain the Aalue of the 

 names used by their ]n-edecessors ; and it by no means un- 

 frequently happens that the efforts of those ]n-edecessors 

 have considerably increased instead of diminishing the 

 Avork to be accomjilishod by their successors. The prac- 

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

 portance 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 cei-tainty as to the s})ecies 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 type specimens, 

 which will, I believe, accomplish their complete ])rotection 

 from all destroying agencies except fire and rude physical 

 catastrophes. Nearly all the smaller species here de- 

 scribed, as well as a considerable proportion of the larger 

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

 bold by the valuable results it promises, I have ventured 

 to describe even minute species where 1 had but a single 

 example of it from which to draw u]) \a\ description. I 

 liave taken some steps to test the efficacy of this mode 

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

 description of the method. 



As regards the terms "• South America " and " tropical 

 America," constantly used in this ]iaper, I should explain 

 that I mean all the parts of the 2sew ^Vorld south of the 

 United States of jS'oi'th America, including the West 

 India Islands, but excluding Chili and Patagonia. The 

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

 the countries on the eastern side of the Andes, and of the 

 Sta])lujlinid(e of Patagonia I know absolutely nothing. 



The 487 species here enumerated are divided among 



