DERMAPTERA AND ORTHOPTERA 263 



ceivably just as old in California and Baja California, has no present 

 day relatives in Mexico proper (its nearest relative is the rare and 

 little known Litoscirtiis of Baja California, which for a number of 

 reasons I feel represents the ancestral line of Dracotettix) . The genus 

 Brachystola probably entered North America in the grass-dominant 

 Pliocene, as it is more frequently encountered in dry or desert 

 grass conditions than the other genera. The ancestral stock of 

 Phrynotettix, which is more truly an arid land genus, may have 

 reached our territory about the same time, as it has developed within 

 our limits two well-distinct specific lines. The genus Tytthotyle has 

 no very close relatives, and may have evolved within our territory and 

 northern Mexico from an old ancestral line, possibly dating back 

 of any of the others. It has a very circumscribed distribution, prefers 

 areas of creosote bush {Covillea tridenlata), and altitudinally does not 

 occur above 2,500 feet, yet is at home under the extremely rigorous 

 conditions on the floor of Death Valley in August. The genus 

 Taeniopoda, represented within our territory by the northern border 

 of the distribution of a widely ranging Mexican species, appears to 

 be a post- Pleistocene intrusive from Mexico. 



(2) Subfamily Cyrtacanthacridinae. The great group of the 

 "spine-breasted" grasshoppers and locusts, which includes many of 

 the world's most important migratory and destructive locusts, is 

 represented in western North America by at least four well marked 

 tribes, the Leptysmini, the Cyrtacanthacridini, the Vilernini, and 

 the Melanoplini. Of these, the Leptysmini and the Vilernini are 

 entirely Neogaeic; the Cyrtacanthacridini, or "bird locusts," are 

 almost entirely Paleogaeic, and chiefly Paleotropical, with but a 

 single genus entering the Western Hemisphere; and the Melanoplini, 

 while predominatingly Neogaeic, also share the Palearctic Region 

 and, more narrowly, the Oriental. 



Of the Leptysmini the single genus Leptysma occurs within the 

 limits of our symposium scope, and is found very locally in suitable 

 areas of tall grass and other vegetation growing generally in standing 

 water (a preferred habitat for members of the tribe, all of which 

 possess definite ability to dive into and swim for short distances in 

 water, usually to rest longitudinally on the stems of grasses or 

 rushes). In the Neotropical Region, particularly in its South 

 American section, are numerous species of Leptysma and certain 

 related genera. Within our territory Leptysma is clearly of Neo- 



