52 UNITED STATES AND MEXICAN BOUNDARY. 
Common about Presidio del Norte, on the Rio Grande, on rocks and mountains, Bigelow ; 
in the lower valley of the Nazas, southeastern Chihuahua, Gregg: fl. May.—Stems 2-4 feet 
high ; joints 2-6 inches long, pale green, without any red or colored spots surrounding the 
pulvillus, as is said to be constantly the case in the allied 0. puberula and O. decumbens; 
leaves very slenderly acuminate, 24 lines long, about twice the length of the axillary wool; 
pulvilli thickly tomentose, and with an abundance of very delicate brown-red bristles, almost 
entirely covering the surface of young or not fully-grown joints; in adult ones about 4 lines 
apart. The flower described above was obtained south of the Rio Grande, in the Bolson de Ma- 
pimi ; ovary 10 lines long, flower 2} inches in diameter, stigmata (green ?) about one line in 
length. This species is nearly allied to O. microdasys, which is common in cultivation, and 
specimens of which from Saltillo I have been able to compare. Our plant has more rounded 
and larger joints, more distant pulvilli, which bear reddish-brown (not yellow) bristles, and 
longer leaves ; from O. puberula, which seems to be yet nearer allied to it, it differs by the 
absence of spines, larger leaves, etc. Mr. Schott has noticed a pubescent Opuntia on the dividing 
ridge of the California Cordilleras, near the boundary line, and a suberect species in the 
Santa Cruz valley, in Sonora, about 3 feet high, both without spines. It is impossible to form 
any opinion where they belong, as no specimens have been saved. 
10. O. Bastuaris, E, & B. in Pacif. R. R.: found by Ur. Schott, in the Gila valley, and up 
the eastern slope of the Californian Mountains ; fl. in May. 
11. O. anewarra (sp. nov.): diffusa, adscendens ; radicibus crassis elongatis seepe stoloniferis; 
articulis minoribus obovatis crassis tumidis seu subcompressis tuberculatis nitide virentibus ; 
foliis minutis pulvillo vix longioribus ; pulvillis subconfertis parce albo-tomentosis setas pluri- 
mas gracillimas pallidas demum in articulis vetustis numerosissimas pulvinatas fulvas gerenti- 
bus, omnibus fere armatis; aculeis superioribus 1-4 sepe subangulatis, summo validiore por- 
recto albido seu fusco-variegato, cwteris brevioribus divergentibus seu deflexis albidis ; aculeis 
inferioribus 2-6 brevibus setaceis albis radiantibus ; floribus sulphureis; ovario obovato pul- 
villis 20-30 setosis aculeolatisque instructo ; sepalis tubi 12-14, inferioribus late obovatis cus- 
pidatis, superioribus obtusis ; petalis sub-8 obcordatis seu emarginatis sepe mucronatis ; stig- 
matibus 5 mucronatis viridibus in capitulum collectis ; bacca oblonga ovata ; umbilico infundi- 
buliformi aculeolis 3-6 ineequalibus deflexis armata; seminibus magnis irregularibus late 
crasseque marginatis. (Tab. LXXV, fig. 15.). Bees fia ee ae 
Sandy bottoms of the Rio Grande near El Paso, Wright: fl. May.—Roots 3-5 lines ‘thick, 
at last ligneous, far spreading in the loose sand, and sometimes stoloniferous, which I have also 
noticed in some forms of 0. Missowriensis ; stems spreading 2 or 3 feet, 4-1 foot high; joints 
14-3 inches long, 1-2 inches wide, often terete or rather oval, or clavate, (a specimen before 
me is 24 inches long and 3 inch thick,) and always strongly tuberculate. Leaves about a line 
long ; pulvilli smaller than in O. Jragilis, very sparingly tomentose, very bristly ; the tawny 
bristles of the old joints covering almost the whole surface. Upper and longer spines 9-15, or 
even 18 lines long, white, with a yellow tip, or brown, yellow, or reddish at base and tip ; ilies 
spines 2-6 lines long, white. Flower 2~2} inches in diameter ; ovary 9-12 lines ay fila- 
ments greenish-yellow; stigmata nearly 2 lines in length. Fruit dry, 10-14 lines in con- 
tracted at top, with a deeply immersed umbilicus, and with spines of 1-5 lines in length ; ‘ke 
aes 7 ‘Kines in diameter. This species is nearly allied to the northern 0. fragilis, but is iat 
guished by the larger and more strongly tuberculated joints, smaller pulvilli set with numerous 
bristles, the longer and slenderer spines, and the spinose fruit. 
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