57 
£V3 
1 . The Atlantic Region ; which has only a single Opuntia , and 
that peculiar to it. Along the Southern coast some West Indian 
species may yet be expected. 
2 . The Mississippi Region, including the Western States, pro¬ 
duces another Opuntia , which, in different distinct forms, extends into 
the 3d, 4th, and 5th regions. 
3. The Missouri Region ; namely, the Northwestern or Upper 
Missouri Territory to the Rocky Mountains. It furnishes 
Two Mamillaria of the subgenus Coryphantha , both extending into 
the 4th and 5th region; and 
Three Opuntia, one of which only is peculiar. 
4. The Texan Region >; namely, the eastern and inhabited parts of 
Texas, westward to the San Pedro, and northward including the terri¬ 
tory south of the Arkansas River. This region produces 
Five Mamillaria , two of them peculiar to this district; 
Three Echinocacti , none of which are found in any other of our 
regions; # 
Six Cerei (five Echinocerei and one Eucereus ), all of them pecu¬ 
liar to this district; and 
Six Opuntia, of which only three are restricted to it; among them 
is only a single cylindric Opuntia . 
This region contains therefore altogether twenty species, fourteen 
of which are peculiar to it. 
5. The New-Mexican Region; namely, Western, uninhabited, 
mountainous .Texas, and Eastern New Mexico to the eastern head¬ 
waters of the Colorado of California. This region is our richest 
Cactus district. It has furnished sixty-five species, fifty-five of which 
are peculiar to it, viz.: — 
Nineteen Mamillaria (eight Eumamillaria , ten Coryphantha , and 
one Anhalonium),oi which sixteen are peculiar; 
Nine Echinocacti , all of them belonging to this district only; 
Sixteen Cerei (fifteen Echinocerei , fourteen of which are peculiar, 
and one Eucereus , common also to other regions); and 
Twenty-two Opuntia; of these twelve are flat-jointed, four clavate, 
and five cylindrical ones: seventeen of these species are peculiar. 
6 . The Gila Region, comprising the whole valley of the Colorado 
# Always excepting Mexico itself, south of the Rio Grande, into which many, if 
not most, of our species extend. 
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