Origin and Diffusion of B/issus leucopterus and Murgantia histrionica . 155 



between the tropical and what we now term the Lower Sonoran life 

 zones, I have indicated by a heavy black line, (see map). This is the 

 geographical division followed by Lichenstein, Swainson, Erichson, 

 Richardson and Darwin, the latter of whom says that here " the great 

 table land presents an obstacle to the migration of species, by affect- 

 ing the climate, and forming with the exception of some valleys and of 

 a fringe of lowland on the coast, a broad barrier.'' It seems that any 

 attempt to pass over this has resulted in specific changes that gave us 

 many of our species, and it is through more stable, generic characters, 

 that we are able to follow much of this considerable portion of our 

 insect fauna to its ancient habitat. LeConte, in his map showing the 

 Entomological Provinces of North America, has shown that a portion 

 of the tropical zone covers the coast area of southern and southeast- 

 ern Texas, while the maps of Packard and Merriam indicate the divi- 

 ding line in Mexico much more clearly. The chinch bug now covers, 

 approximately, the eastern division of the United States as indicated 

 on the map of LeConte, as published in 1859 by the Smithsonian 

 Institution. 



Mr. L. O. Howard, United States' Entomologist, has kindly aided 

 me in looking up the references in Biologia Centrali-Americana, a work 

 to which I did not have access ; and for the present distribution of this 

 species in North America, I am indebted for information to Mr. 

 James Fletcher, Entomologist of the Dominion of Canada, Profs. 

 Lugger of Minnesota, Brunert of Nebraska, Gillette of Colorado, 

 Neal* of Oklahoma and Cockerell of New Mexico. 



Since the above paper was presented, Mr. John R. Chandler, 

 State Archaeologist of Guatemala. Central America, has kindly given 

 me the locations and elevations of the localities where Blissus leuco- 

 pterus is recorded as occuring in that county by Mr. Champion. 

 (Biologia Centrali-Americana, vol. I. p. 196.) 



San Geronimo, interior, elevation about 3.000 feet. 



Paso Antonio, ? . ? 



Panzos, low, near river emptying into the Atlantic, elevation about 2,000 feet. 



Champerico, Pacific coast, elevation sea-level. 



Rio Naranjo, near Pacific coast, ...... elevation about 2,000 feet. 



F. M. W. 



*Lately deceased. 



