528 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



At the beginning of this century Stal, a great Swedish hemipterist, com- 

 menced his work. Perhaps no student of the order Homoptera has had a better 

 grasp of the fundamental groups and the fundamental phylogeny. He was ably 

 assisted by a fairly large group of students of Homoptera in Europe, including 

 Walker and Marshall of England, Signoret of France, and Fieber of Germany. 

 Most of these men had ceased publication by the end of the second decade of the 

 century. In America at this same time the most outstanding student of this order 

 was Fitch in New York. 



Walker worked on the extensive collections in tlie British Museum and de- 

 scribed many new genera and numerous new species from all parts of the world. 

 Unfortunately, he did not seem to have a clear concept of taxonomic units. He 

 made numerous mistakes in assigning species to genera, and formerly it was 

 quite the fashion to condemn his v/ork universally; however, recent students in 

 restudying his material have had a better appreciation of his work. Marshall 

 worked on a taxonomic review of the species then known from Great Britain 

 and contributed a sound foundation on which future students of the British 

 fauna could work. Signoret's studies were most extensive in his reviews of the 

 genus then known as Tettigonia and related genera, and of the species which 

 he considered closely related to the genus Acoceplialus. Fitch's catalogue of the 

 specimens in the State Cabinet of Natural History, with careful descriptions of 

 the species known to him, was the foundation for future studies by American 

 homopterists. 



After this first period in the development of taxonomy in relation to the 

 Homoptera, the large number of workers as well as their increased specialization 

 makes it difficult to summarize the contributions of each student. I have simply 

 listed these workers, therefore, together with the years during which they made 

 their principal contributions, and will leave it to the individual student to 

 make his own summary. 



The next three decades showed a large increase in the number of students 

 who devoted their primary energy to this order. During the first two decades 

 these students devoted their time principally to the larger and more conspicuous 

 species. Beginning about 1870 more emphasis was placed upon the local faunas 

 of the various European countries, and of the United States and Argentina in 

 particular. Some of the outstanding students of this time and the periods of 

 their contributions were the following: Ashmead, 1880-1900; Berg, 1879-1899; 

 Distant, 1878-1920; Edwards, 1877-1928; Horvath, 1871-1931; Lethierry, 1869- 

 1894; Melichar, 1896-1932; Puton, 1869-1899; Scott, 1870-1886. 



From 1900 on there has been a great tendency to discuss or to review single 

 genera and their species, usually from a restricted area: Baker, 1895-1927; Ball, 

 1896-1937; de Bergevin, 1910-1934; Breddin, 1896-1905; Buckton, 1889-1905; 

 Davis, 1885-1942; Fowler, 1894-1909; Funkhouser, 1913-1951; Goding, 1890- 

 1939; Jacobi, 1902-1941; Kirkaldy, 1899-1913; Lallemand, 1910 to date; Mat- 

 sumura, 1898 to date; Osborn, 1884 to date; Edmund Schmidt, 1904-1937; Swe- 

 zey, 1903-1942; Van Duzee, 1888-1940. 



Since about 1920 more and more studies have appeared on the internal male 

 genitalia as the court of last resort in defining species. Some of the principal 

 workers of this era are the following: Beamer, 1924 to date; China, 1923 to date; 

 De Long, 1916 to date; Esaki, 1922 to date; Evans, 1931 to date; Fennah, 1939 to 



