Yar. a. nigricans : aculeis brevioribus acute angulatis et nigri- 
cantibus. 
Yar. 0. brtjnnea : pulvillis remotioribus ; aculeis Iongioribus obtuse 
angulatis brunneis sursum albidis. 
Yar. y. major : suborbiculata; pulvillis .remotis ; aculeis breviori¬ 
bus paucioribus pallid ioribus. 
New Mexico: fl. May. Yar. a. is found on the Rio Grande near 
Santa Fe; /3. in similar sandy locations near El Paso; and y. in 
mountainous regions near Santa Fe. —Joints 4-6, or in y. even 8, 
inches long; spines mostly 1-2 inches in length. Flower about 2 
inches in diameter, with a short ovary. Fruit 1J-1J inches long, 
Slender, much contracted at base so as to appear almost stipitate. 
O. Mojavensis, E. & B. in P. R. R.: prostrata; articulis grandi- 
bus suborhiculatis; pulvillis remotis ; setis fulvis; aculeis 3-6 validis 
infra fuscis. 
On the Mojave, west of the Colorado. — The material is too scanty 
to make out where it belongs; but perhaps it is only a form of 
0. phceacantha. 
f 11. O. Camanchica, E. & B. ill P. R. R.: prostrata; articulis 
adscendentibus majusculis suborbiculatis ; pulvillis remotis plerisque 
armatis; setis stramineis fulvisve parcis ; aculeis 1-3 compressis 
fuscis apice pallidioribus, superioribus elongatis suberectis, cseteris 
deflexis; bacca ovata late umbilicata; seminibus majusculis angu¬ 
latis hilo excisis. 
Llano Estacado, on the Upper Cana.dian River. A large, exten- 
I sively spreading plant; the joints 6-7 inches long ; spines 1J-- 2 or 
even 3 inches long. Fruit large, juicy. Seeds 2-3 lines in diame¬ 
ter, very irregular and deeply notched at the hilum. 
12. O. TORTispiNA, E. & B. 1. c.: prostrata ; articulis adscendenti¬ 
bus majusculis suborbiculatis ; pulvillis subremotis ; setis stramineis 
seu fulvis ; aculeis 3-5 majoribus angulatis ssepe tortis albidis cum 
2-4 gracilioribus ; bacca ovata late umbilicata ; seminibus majuscu¬ 
lis orbiculatis. 
On the Camanche plains, east of the elevated plateau of the Llano 
Estacado. — Similar in size and habit to the last species, its western 
neighbor, with more numerous spines than any other of our Opuntice 
with juicy fruit. Seeds regular, and only very slightly notched at 
the hilum. 
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