qd 
Var. a. RUFISPINA, E. & B,: articulis orbiculatis ; aculeis interiori- 
bus 3 —5 validis fuscis; bacca ovata. 
Var. 8. pLatycaRPA, E.: articulis obovato-orbiculatis ; aculeis in- 
terioribus subsingulis validis fuscis; bacca depresso-globosa late um- 
bilicata. 
Var. y. MIcROSPERMA, E. : articulis aculeisque preecedentis ; bacca 
ovata breviter aculeolata ; seminibus minoribus anguste marginatis. 
Var. 6. sUBINERMIS, E.: articulis elongato-obovatis, pulvillis sub- 
remotis inferioribus inermibus, superioribus aculeos paucos breves 
gerentibus. 
Var. «. ALBISPINA, E. & B.: articulis late obovatis; aculeis 6— 12 
omnibus albis gracilioribus ; bacca ovata. 
Var. ¢ TRIicHorHoRA, E. & B.: articulis ovatis; pulvillis confertis ; 
aculeis 10-18 setiformibus (in articulis vetustis numerosicribus) capil- 
laceis flexuosis ; bacca ovata; seminibus maximis. 
From the Upper Missouri to the Canadian; principally occupying 
the western plains, but also on the mountains towards Santa Fé and 
west of it.— The last-mentioned variety (which I would consider 
a distinct species, were it not for the var. albispina, which seems to 
unite it with the others) has been found only on the mountains near 
Albuquerque : all the other forms occur on the Upper Missouri, and 
a, and e. also on the Canadian. Other and intermediate forms of this 
variable but nevertheless well-characterized species will no doubt be 
found in the wide territory inhabited by it. It flowers in May and 
June. — Joints 2-4, rarely 4-6 inches long, and 2 — 3} inches wide, 
light green ; leaves 14-2 lines long; larger spines 1 — 14, rarely 2 
inches long, in 6. not more than 3-6 lines long. Flowers 2-3 
inches in diameter, with short green stigmata forming ‘a compact 
head. Fruit 1-1} inches long, with shorter or longer spines, and a 
rather shallow umbilicus. Var. 8. has a remarkably large flat fruit. 
Seed generally about 3 lines, but in y. only 2 lines, in diameter. 
24. O. spH#Rocarpa, E. & B. 1. c.: diffusa ; articulis orbiculatis 
tuberculatis ; pulvillis confertis stramineo-setosis plerisque inermibus, 
summis solum aculeos 1-2 deflexos patulosve majores gerentibus, 
adjectis sepe 1-3 brevioribus; bacca globosa vix aculeolata ; semi- 
nibus mediis. 
Mountains near Albuquerque, New Mexico. — Joints 3 inches in 
diameter, strongly tuberculated; pulvilli 4 or 5 a apart; spines 
6 — 12 lines long, reddish-brown, often single or 2 or 3 together, with 
