BAILEY: THYSANOPTERA 525 



merman (1942-1948) in this country, and of Ball (1926-1940, Belgium), Pear- 

 man (1924-1951, England), Badonnel (1939-1951, France), and Roesler (1935- 

 1944, Germany) abroad. Numerous observations on biology have appeared since 

 the turn of the century and these, along with the genitalic studies, have been 

 used in developing a new framework for classification, founded on general mor- 

 phology, as outlined by Pearman (1936), then modified and expanded by Roes- 

 ler (1944). There still remain imperfections at some points. Since 1903 well 

 over three hundred psocid papers have been published, about one-sixth of which 

 are contributions from the United States. At the present time there are about 

 1,200 described species composing nearly 230 genera in 26 families; of these the 

 United States claims 11 families, comprising 30 genera and 135 species. The main 

 United States collections of native psocids are located at Cambridge, Massachu- 

 setts (Museum of Comparative Zoology) ; Washington, D. C. (U. S. National Mu- 

 seum) ; Urbana, Illinois (Illinois Natural History Survey) ; Geneva, New York 

 (Chapman Collection), and Orlando, Florida (Sommerman Collection). 



In the future much emphasis will be placed on comparative morphology, 

 biologj^ and geographic distribution. Careful dissection is an indispensable pre- 

 requisite for morphological studies, and progress would be accelerated if a 

 trouble-free permanent mounting medium of low refractive index could be de- 

 veloped for the preservation of reference microscope preparations. 



THYSANOPTERA 



Stanley F. Bailey 

 University of California, Davis 



Most specialists in the order Thysanoptera recognize as milestones the de- 

 scription of the first thrips by De Geer in 1744 and the proposal of the ordinal 

 name by Haliday in 1836. Linnaeus, Fabricius, Latreille, and Burmeister clas- 

 sified this group of insects with the early hemi-homopteroid or orthopteroid 

 groups. Westwood in 1840 presented one of the first outlines of the order with 

 a summary of its taxonomic evolution. In 1895 Uzel published the first compre- 

 hensive review of the order with keys which, together with Hinds' (1902) classic 

 review of the group in North America, stimulated entomologists to take up 

 the group. 



Up to this time a bare skeleton of families with scattered genera made up 

 the somewhat shaky taxonomic framework of the order. After the turn of the 

 century the main work of filling in the great gaps was carried by Moulton ( 1907- 

 1939), Karny (1908-1928), Bagnall (1908-1936), Watson (1913-1946), and 

 the two outstanding living world authorities, Priesner (1914-) and Hood 

 (1908-). The synopses, keys, monographs, and descriptions of hundreds of 

 species of these workers make up the greatest part of the knowledge of Thysanop- 

 tera. However, there has been a tendency to create new families and groupings 

 when bizarre, widely separated genera are found. Priesner, in his Genera Thy- 



