8 M. W. NIELSON 



Tharrini are Australian and Oriental and rarely occur north of the 20th parallel 

 in the Northern Hemisphere and south of the 20th parallel in the Southern Hemi- 

 sphere. Only one species based on a single specimen is in the Ethiopian Region, 

 and this record is considered doubtful. 



The large genus Tharra and its relatives occupy the subregions of Melanesia, Micro- 

 nesia, New Guinea, Indonesia, southern Philippines, and Malaysia of the Oriental 

 region. Its rare occurrence in northern Australia and proliferation in the subregions 

 are indicative of Indo-Malayan origin. 



TECHNIQUES 



The details of preparation of genital structures of leaf hoppers for dissection and 

 study are given by Oman (1949) and Young & Beirne (1958). I have followed 

 their methods with some modifications. The bodies of most coelidiine leafhoppers 

 are heavily sclerotized and require a long time for potassium hydroxide solution 

 to clear the internal viscera. A system was devised in which the abdomens of 

 40-50 coded leafhoppers were cleared simultaneously by allowing the structures 

 to soak overnight at room temperature in a saturated solution of potassium hydroxide. 

 The following day individual abdomens were washed in distilled water, transferred 

 to ten per cent acidulated water, then washed in distilled water before examination 

 and storage in glycerated microvials. 



ILLUSTRATIONS 



All illustrations were prepared freehand with the aid of an ocular grid. The 

 internal male structures were drawn at ocular magnifications of x 90 to X 120 

 and the external structures at lesser magnification, depending upon the size of the 

 species. The characters illustrated are not always shown in detail, particularly 

 setae which were too numerous on the male pygofer and plate. The female seventh 

 sternum was included whenever it was diagnostic. 



ACKNOWLEDGEMENTS 



This work would not have been possible without the generosity of many 

 individuals who contributed their time and talents to the various phases of this 

 work. 



I am especially grateful to the American Philosophical Society of Philadelphia, 

 who supported this study in part by grant No. 6151 of the Penrose Fund and whose 

 financial assistance made it possible for me to travel to many countries in Europe 

 to study type-material. 



I am especially indebted to Dr James P. Kramer of the U.S. Department of 

 Agriculture, whose encouragement stimulated the completion of this work and 

 who read the manuscript and made many useful suggestions. I am also indebted 

 to Dr David R. Ragge, British Museum (Natural History), for editing the manu- 



