88 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



FAMILY DISTRIBUTION AND FAUNAL AREAS. 

 BY NATHAN BANKS. 



All of us have looked at the prettily colored maps of the 

 fauual areas of the world or of parts of it, arid have wondered 

 at the windings of black lines up and down and across the 

 map and have admired the genius that constructed the plan. 



But I think that nearly all who have taken some interest in the 

 geographical distribution of certain restricted groups have 

 concluded that their particular group was of abnormal distri- 

 bution; that it did not follow the maps. 



These faunal maps have been made mostly for the larger 

 animals, and doubtless for tht-m fairly accurate. It is my pur- 

 pose to show in this paper that any one map of faunal areas 

 will not explain the distribution of all groups. In other 

 words, the faunal areas vary with the family, or even genus. 

 If, for example, we consider the distribution of the neurop- 

 terous family Panorpidae (scorpion-flies) in our country the 

 first point we note is the great distinction between the Eastern 

 States and the Western Region. The largest genus, Panorpa, 

 is common all through the Eastern States, and absent from 

 the Western States, unless a Mexican species may occur in 

 Southern California. The genus Bittacns is also common in 

 the East, but not very common in the West, and there repre- 

 sented by peculiar forms. The genus Boreas occurs across 

 the northern part of the United States, as common in the 

 Northwest as in the East. The genus Panorpodes has but 

 two species one in North Carolina, one in Oregon. There 

 is nothing in this distribution to show the relation of the Cal- 

 ifornian fauna to that of Europe, for Panorpa is common in 

 Kurope, and their Bittacus are more like our Eastern species 

 than like the Western ones. 



If we look at the species of Panorpa we can readily see 

 faunal areas in the East. So if one were to map the distribu- 

 tion of our Panorpidse he must show the distinctness of the 

 eastern and western regions and that the eastern region is 

 more like that of Europe. 



If, for example, we consider the distribution of another 

 neuropterous family, the snake-flies (Raphidiidse), we come to 

 very different conclusions. This family has many species in 

 Europe; in America they are common in the Western States, 

 absolutelv absent from the Eastern States. Neither is it a 

 family of boreal distribution, for none occur far north and one 

 occurs in Baja California. As with the Panorpida?, one must 

 emphasize the difference between Eastern and Western faunas, 

 yet the Western is the one with relations to Europe. 



