50 UNITED STATES AND MEXICAN BOUNDARY. 
plerisque armatis; aculeis 2-5 rectis superiore teretiusculo porrecto, ceteris brevioribus ins- 
qualibus plus minus angulatis seu compressis deflexis fuscis seu fusco-atris sursum pallidioribus ; 
flore flavo; ovario brevi pulvillis sub-20 tomentosis et fulvo-setosis versus superiorem ovarii 
partem congestis ; sepalis tubi sub-13 exterioribus late oblanceolatis ceteris late obovatis cuspi- 
datis ; petalis 8-10 late obovatis obtusis submucronatis ; stigmatibus 8 erectis ; bacca cuneato- 
pyriformi late umbilicata vix pulposa; seminibus plerumque majusculis sub-regularibus crasse 
marginatis. (Tab. LXXV, fig. 9-13.) 
Var. a, NIGRICANS: obovata, viridior ; pulvillis magis approximatis ; aculeis brevioribus acute 
angulatis nigricantibus. 
Var. 8. BRUNNEA: obovata, glaucescens ; pulvillis remotis; aculeis longioribus obtuse angu- 
latis infra brunneis. 
Along the Rio Grande near Santa Fé, var. a. Fendler ; var. 2. common about El Paso, on the 
sandy ridges in the immediate valley of the river, Wright.—The northern plant has been cor- 
rectly described in Plante Fendleriane, with the exception of the flower, which probably refers 
to O. Missouriensis, or some allied species. The variety from El] Paso has remarkably thick and 
glaucous joints, which in fall and winter often assume a purplish hue; they are commonly 4 or 
5 inches long, and 25-3 inches wide ; the largest ones were 7 inches long, and 43 inches broad ; 
sometimes they are more orbicular and shorter; leaves 23-3 lines long, thick in proportion ; 
pulvilli 1-13 inch apart, with dirty yellowish or brownish bristles ; only the lowest ones 
without spines; spines usually 2-4, sometimes 4 or 5, and even more, in one bunch, 1-2 or 
sometimes 24 inches long, terete or more or less flattened, but without sharp angles, often 
striate, light or dark brown below, whitish above ; lower spines often entirely whitish. Flower 
24-23 inches in diameter ; ovary 10 lines long, 8 lines in diameter; fruit 1}-14 inch long, 
with the lower part contracted, solid and seedless 3 umbilicus rather shallow ; seeds very vari- 
able, usually over 2 lines in diameter, but sometimes smaller. 
6. O. TENUISPINA, (sp. nov.): diffusa seu adscendens ; articulis mediis seu majusculis obovatis 
basi attenuatis late viridibus ; foliis gracilibus subulatis parvis, pulvillis subapproximatis setas 
breves graciles fulvas rufasve gerentibus, plerisque armatis seu inferioribus inermibus ; aculeis 
si apiceque fuscatis 
singulis binisve teretiusculis rectis gracilibus flexilibus albidis non raro ba 
annulatisque, adjectis sepe inferioribus tenuioribus albis, superiore in areolis superioribus por- 
recto, ceteris deflexis ; ovario clavato gracili pulvillis 25 versus apicem aggregatis griseo-villosis 
et fulvo-setosis stipato; sepalis tubi sub-13 obovato-orbiculatis abbreviatis cuspidatis ; petalis 
13 obovatis sub-emarginatis mucronulatis flavis basi aurantiacis ; stigmatibus 7-8 sacle vires- 
-centibus ; bacca minore oblonga profunde umbilicata, seminibus minoribus irregulariter angu- 
latis anguste marginatis. (Tab. LXXYV, fig. 14.) 
Sand-hills on the Rio Grande, near El Paso, from Doiia Ana to San 
About a foot high, spreading ; joints 3-6 inches long, 2—4 inches wide ; leaves 2 lines long, or 
less, } line in diameter; pulvilli 3 inch, or, in the largest specimens, almost an inch apart witli 
short grey wool, and bright, reddish-brown, slender bristles, 1-1} line long ; spines stiff and 
very straight, but flexible; lowest ones 3-1} inch long ; upper ones 13-24 a rarely even 3 
inches long, whitish, or, in some species, brown towards the base, or on the neds sed always 
darkish at tip; flower 21-3 inches in diameter ; ovary 1-1} inch long, slender : Bipate re- 
markably short ; petals rounded or somewhat emarginate, 1-1} inch long, 6-9 ids broad 
yellow, with orange-red at base, turning all red on the second day of flowery: Fruit Ly 
Elizario, Wright; fl. May.— 
