532 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



have received only cursory attention. The life history of the seventeen- and 

 thirteen-year cicadas in North America is well known owing to the comprehen- 

 sive studies of Marlatt. Osborn and Ball made very great contributions to the 

 life histories of the leafhoppers in Iowa many years ago, and Osborn studied 

 the life histories of the leafhoppers of Maine and the froghoppers of the same 

 region. More recently some contributions liave been made to the life history 

 of the alfalfa froghopper. Some general studies of the life histories of the tree- 

 hoppers were made many years ago by Funkhouser, and some of the economic 

 pests in this group have been rather generally studied. Much still remains to 

 be done, especially in the tropical regions of the world. The fulgorids have been 

 rather generally neglected; the life histories of only a few species have been 

 studied and these rather incompletely. 



The phylogeny of the group as a whole is rather poorly understood. Most 

 of our present-day discussions are based upon the studies of Stal, made nearly 

 100 years ago. Less than 500 of the present known 3,500 genera and perhaps 

 less than 4,500 species of the known 30,000 species were then known. Stal con- 

 ceived the group as comprising four families and for the most part we now con- 

 sider these of superfamily or even higher rank. Basing our studies of the group's 

 phylogeny on such a small area of the total population would be like basing 

 our studies of geography on the knowledge of geographers of the world before 

 the discovery of America by Columbus, or basing our studies of history on only 

 the history known before the beginning of the Christian era. 



Fairly comprehensive studies of the genera of Fulgoridae by Muir and 

 others, of the Cercopidae by Lallemand, of the jassids by Evans, Oman, and 

 others, and of the Membracidae by Funkhouser give a rather firm basis for com- 

 prehensive study of the phylogeny of these groups. Perhaps what is most needed 

 now is research on the phylogeny of the families and of the groups higher than 

 the families. For the present I believe that the knowledge of the subfamilies, 

 perhaps of the tribes, of most of the groups is fairly comprehensive. 



What, then, of the future? AVhat the future holds for the field of taxonomy 

 is anybody's guess. Whether other characters will influence the taxonomy of the 

 group as profoundly as the discovery of the impoi'tance of male genitalia has 

 influenced it in the last quarter century remains unknown. Yet I believe that 

 other characters quite as important as the morphology of the male genitalia will 

 be discovered in the not too far distant future. 



The present tendency is to confine taxonomic studies to a single genus re- 

 stricted to a limited area of the world's surface. Perhaps this is the best method 

 for making progress. It is unfortunate, however, that so few students are suf- 

 ficiently interested in the suborder as a whole to devote their time and attention 

 to the groups higher than genera. Very little progress in taxonomy is going 

 to be made until we have a thorough restudy of at least the external morphology 

 of these interesting insects, correlated perhaps with a study of the internal mor- 

 phology, of physiology, embryology, ecology, and zoogeography. This, indeed, 

 sounds like a comprehensive program but as long as our knowledge of taxonomy 

 is based upon the phylogenetic concepts of Stal of one hundred years ago and as 

 long as we confine the insects of this group to four or five families, just so long 

 will our taxonomic concepts be inadequate, for the consideration not only of the 

 species already described, but of the genera and species not yet described. 



