340 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



separate the species but also to those which two or more species may 

 have in common. This approach appears to be estabhshing a series 

 of genera that are not only composed of "closely related" species 

 but that also have restricted ranges of some zoogeographical signi- 

 ficance. 



At the species level there has been much confusion and great 

 uncertainty concerning the application of trivial names. In great 

 part this uncertainty has been due to the fragmentary and at times 

 inaccurate original descriptions, and in part to the assignment of 

 forms to the wrong genus. Many of the keys that have appeared 

 have been drawn from misdetermined material and so could only 

 lead to further error. Even some of America's outstanding hemip- 

 terists have been inconsistent in their assignments of names so that 

 in the material available for study some species were determined 

 first as one thing and later as another by the same worker. This 

 point is brought up not to condemn the work of these men, but 

 simply to show that even careful students were confused by the 

 literature. Probably the most misused name in the cydnid literature 

 of the Western Hemisphere was Uhler's Pangaeus discrepans. It 

 was found attached to no less than six distinct species in three 

 different genera, while specimens of true discrepans were found under 

 three other names as well as the proper one. The most accurate 

 determinations appear to have been made on those species which 

 could be placed chiefly on distribution and with a minimum of 

 morphological characters. With the literature and the work of 

 specialists leading to such muddled results, the group has been in 

 dire need of a thorough revision. 



The present study is a revision of the known species of all included 

 genera except Sehirus, of which only 1 of the 24 or more nominal 

 species occurs in the Western Hemisphere. 



The specific descriptions include the mean and extremes of measure- 

 ments, in millimeters, from five individuals of each sex unless otherwise 

 indicated. The color, unless otherwise stated, may be assumed to 

 be the usual brownish black to black (yellow or light brown in teneral 

 specimens) without conspicuous or important markings. The follow- 

 ing abbreviations are used to indicate the collections in which speci- 

 mens are housed. 



AmN: American Museum of Natural Carv: J. C. M. Carvalho 



History CIS: California Insect Survey 



Bon: F. Bonet Copen: Universitetets Zoologiske 

 BrM: British Museum (Natural Museum, Copenhagen 



History) HMH: H. M. Harris 



CalAc: California Academy of Sciences Hung: Musee d'Histoire Naturelle de 

 Cap: J. M. Capriles la Hongrie 



Car: Carnegie Museum Ind: University of Indiana 



