LYMNZID OF NORTH AMERICA. 59 
part of southeastern California, the extreme northwestern part of 
Mexico and the whole of Arizona. 
9. Great Basin. This includes the desert and arid regions of 
Nevada, Utah, Oregon and California. There is no outward drainage. 
A number of lakes occupy this basin, of which Great Salt Lake is the 
largest. 
10. CALIFORNIAN. This area includes the coastal portions of 
Oregon and California, as well as that portion of the states west of 
the Sierra Nevada and Cascade ranges. The Sacramento and San 
Joaquin are the principal river systems. Its southern extension reaches 
the northern part of Lower California. 
11. Rio GranptaAn. This includes the basins of the Rio Grande 
and the Pecos River, with their tributary streams. It embraces the 
southern part of Colorado, nearly the whole of New Mexico, the 
western part of Texas and the northern and central parts of Mexico 
drained by the tributaries of the Rio Grande. It includes the higher 
Mexican plateau. 
12. Upper MississtppIAN. This area includes the territory 
drained by the upper Mississippi and Missouri rivers, including their 
tributary streams. It embraces the country south of the “Height of 
Land” in southern Canada and the Great Lakes, all of the territory 
between the Rocky Mountains on the west and the Appalachian Moun- 
tains on the east, and north of about the 35th parallel of north latitude. 
The drainage areas of the Arkansas and Tennessee rivers form the 
southern boundary of this area, and the line of the water partings 
varies from the 35th to the 38th parallels. The Ozark Mountains also 
inark the southern limits of a portion of this region. 
13. Lower MississippiAn. This includes the region south of the 
Arkansas and Tennessee rivers. Its western limit is the Great Plains 
east of the Rio Grande drainage. Its eastern limit is somewhat indefi- 
nite, but would seem (judging by the distribution of certain Lymnzeas ) 
to be north of the St. Johns River in Florida, where a line drawn north- 
ward to the Appalachian range would separate the Lower Mississippian 
from the Carolinian region. This region embraces the lower drainage 
areas of the Mississippi River as well as all of the rivers flowing into 
the Gulf of Mexico, east of the Rio Grande. It includes also the entire 
peninsula of Florida. 
14. CarotiniAn. This area includes all of the coastal strip east 
of the Appalachian range from southern New Jersey south to the St. 
johns River, Florida. The drainage is into the Atlantic Ocean. Its 
northern limit is marked by the Potomac River, whence the line of 
