EDMUNDS: EPHEMEROPTERA ^^l 



also proposed a new family, Siphloplectonidae, but in tlie writer's opinion the 

 division is unnatural, and Siphloplectonidae is a synonym of Metretopodidae. 



In his fine report on the mayflies of the Sunda Islands, Ulmer proposed a new 

 subfamily of Siphlonuridae, Pseudoligoneuriinae, for Pseudoligoneuria, known 

 only from an oligoneurid nymph w^hose incipient venation appears to be of the 

 siphlonurid type. In 1943, Spieth transferred the subfamily to the Oligoneu- 

 riidae. Only three years before his death in 1945, Lestage proposed creation of 

 the family Tricorythidae for a group of genera bearing remarkable convergent 

 similarity to the Caenidae. The most recent proposed change in the classification 

 is the relegation of Metretopodidae to a subfamily of the Siphlonuridae by De- 

 moulin in 1952, ])ut the desirability of such a move seems questionable. 



The families have had a stable existence when compared to groupings above 

 family level. As with the families there has been little agreement on the taxo- 

 nomic level given such complexes of families. They have been ranked as groups, 

 subfamilies, families, superfamilies, or suborders. Oddly enough, the great ma- 

 jority of all workers have regarded the mayflies as being of three great sections, 

 although two, four, five, or six have been indicated by others. But there has 

 been little agreement on the composition of these groups, and, with our present 

 knowledge, stability is neither expected nor desired for some time to come. 



As in most orders, the preponderance of the papers on Ephemeroptera has 

 been dedicated to a limited area of the world, and thus, though there are great 

 gaps in our knowledge, some areas have become well known. As is to be ex- 

 pected, the western Palearctic region is best known, as a result of many fine 

 papers produced there by the numerous authorities. The eastern Palearctic 

 region has been rather neglected by comparison. Except for studies of some of 

 the Indian mayflies and the fine works by Ulmer on the Sunda Islands, the 

 Oriental region also has been rather neglected. The Australian and New Zea- 

 land species have been reported upon by several competent specialists, but revi- 

 sions are needed of this critical fauna. The mayflies of the Ethiopian and Neo- 

 tropical regions are known chiefly from specimens that have come to the cabi- 

 nets of European and American workers, but exceptional regional studies have 

 been done on South Africa, Brazil, and Porto Rico. 



The North American mayfly fauna is certainly one of the most extensively 

 studied, but great geographical areas I'emain unworked. The first detailed study 

 upon the mayfly fauna of any state was done by J. R. Traver in North Caro- 

 lina, and other detailed studies have followed, the most notable being the re- 

 cent reports on the Florida fauna by Berner and the Illinois form by Burks. 

 Drs. McDunnough and Ide also have made extensive studies in certain parts 

 of Canada. 



Aside from the need for collecting and describing the mayfly fauna of the 

 little known geographic areas of the earth and continuing the description of 

 immature forms, there are many other fertile fields of study on this order of 

 insects. Phylogenetic studies are most desirable. The present arrangement of 

 families leaves much to be desired, and the grouping of families into larger 

 groups is not satisfactory. Instead of confining studies by setting geographic 

 boundaries, future workers will find it more productive to confine themselves 

 to a systematic unit and ignore political subdivisions. Revisions of many genera 

 are sorely needed; for example, I am aware of three congeneric species that are 



