TAXONOMIC MORPHOLOGY 13 



and also by the necessity of using Raff ray's keys to the world fauna in a com- 

 pilation of genera of pselaphids by Bradley (1930). Both Blatchley and Brad- 

 ley used the scattered work of Casey where feasible. 



Monographically speaking, then, the pselaphids had not been coordinated 

 between 1890 and 1934, when John R. Bowman gathered the scattered literature 

 of the family, and drew up keys from descriptions of species. 



Henshaw (1885) numbers 136 species and varieties of pselaphids, divided 

 among 29 genera. Leng (1920) in his admirable Catalogue numbers 364 spe- 

 cies and varieties, divided among 63 genera. This was an increase of 167 percent 

 species and 117 percent genera between 1885 and 1920. Taking the 1920 figures 

 of Leng, we find that LeConte described 81 species and 12 genera, Brendel 63 

 species and 8 genera, and Casey 181 species and 22 genera. Thus these three 

 students described 325 out of 364 species, and 42 out of 63 genera. Since virtually 

 all of the LeConte and Brendel species and genera were listed by Henshaw, 

 we note that the total increase to 1920 was largely a consequence of Casey's 

 taxonomic activity. 



In addition our knowledge of North American Pselaphidae has been ma- 

 terially added to since 1900 by shorter contributions, among which may be 

 mentioned the revision of Adranes by Wickham (1901) ; addition of the tribe 

 Holozodini by Schaeffer (1906) to the pselaphid fauna of the United States in 

 the description of the new species Caccoplectus spinipes; the revision of 

 Rybaxis by Fall (1927) and of Rhexidius by Fletcher (1932). In this latter 

 paper, Fletcher described Hamotus {H amotoides) opimus from Florida. This 

 was the first time that a member of this large, typically neotropical aggregate 

 had been definitely recorded north of Mexico. 



That portion of the Americas in which this study is especially concerned, 

 from the Rio Grande southward through Argentina, has received no mono- 

 graphic treatment, nor can any be contemplated for many years. Much of the 

 region is occupied by the neotropics, and the pselaphid fauna of the equatorial 

 rain forest and tropical savanna remains largely unknown. The most am- 

 bitious effort was that of David Sharp (1887) in the Biologia, covering the 

 area from the northern boundary of Mexico to Panama. Unfortunately the 

 lack of keys, the short and vague descriptions, and the generalized figures 

 render this study less valuable. Of much more practical worth are the short 

 generic studies and description of new species by Raffray (1891, 1896, 1897, 

 1903, 1904, 1909, 1911, 1917) and the modern work of Bruch, Reichensperger, 

 and Fletcher (1927, 1928, 1928a, 1930). 



The extent to which the pselaphid fauna of the neotropics remains un- 

 known may be partially realized by considering the amount of new material 

 discovered in several expeditions. In the Biologia, Sharp (1887) listed 98 

 species, of which 70 were new. In an expedition to Venezuela, Simon found 39 

 species, of which 33 were new (Raffray, 1891). The Cornell University expe- 

 dition to South America returned with 11 species of Pselaphidae. Of these 

 two could not be identified beyond the genus, and of the nine which could be 

 identified, seven were new (Fletcher, 1928). In a study of Barro Colorado 



