less of its form. Some of these varieties may prove to be valid species 

 on further study, and then may be given latinized designations. 



Primary homonyms of species have been replaced by nomina nova; 

 secondary homonyms have been restored to their original names if the 

 homonymy has been relieved by moving one or the other, or both 

 species, to other genera. 



All specific endings have been modified to agree with the suggestions 

 made by Blackwelder 1940, Journal of the Washington Academy of 

 Sciences 31: 135-140. There are certain disadvantages inherent in 

 this method, but it seems to the writer that these limitations are out- 

 weighed by the advantages. We are confronted by so many coined 

 words that can have no gender, it seems better to use this system and 

 disregard apparent violations of Latin and Greek grammar. Where 

 the gender of generic names can be determined, the appropriate adjust- 

 ments are made in the specific names. 



In a detailed catalogue such as this, it is practically impossible 

 to eliminate all errors. We will appreciate it very much if our at- 

 tention is directed to all such mistakes. It is especially easy to 

 overlook local lists published in the proceedings of local natural his- 

 tory societies, references to species of economic importance published 

 in scientific agricultural journals, references to vectors of plant dis- 

 eases published in phytopathological journals, and references of a 

 similar nature. It will be very much appreciated if authors will send 

 us reprints of all articles dealing with the Homoptera. Also, it 

 would seem that no changes in the nomenclature adopted in this 

 catalogue should be made in the future without a full explanation. 



All literature available to the writer before December 31, 1955, has 

 been included in this catalogue. 



The present catalogue of the Family Hylicidae is the second part 

 of the Cicadelloidea. This was virtually complete at the time of 

 the death of Dr. Z. P. Metcalf on January 5, 1956. It was completed 

 with the aid of Miss Virginia Wade, research analyst, North Caro- 

 lina State College, who worked with Dr. Metcalf for 7 years, and 

 the technical advice of Dr. David A. Young, Jr., North Carolina 

 State College, and Dr. P. W. Oman, formerly with the Insect Iden- 

 tification and Parasite Introduction Research Branch, Entomology 

 Research Division, U.S. Department of Agriculture, Beltsville, Md. 

 The higher categories utilized in this classification are those decided 

 upon by Dr. Metcalf during his work on the catalogue. 



In this part of the catalogue a method of literature citation has 

 been adopted which differs from that used in the catalogues of the 

 fulgoroid families. This change has been instituted to save time, 

 space, and publication costs. It is believed that the revised method 

 will cause no great inconvenience to the reader. Dr. Metcalf himself 



