45 3*/ 
or without smaller ones, which never occurs in any form of O. Mis- 
souriensis , where a large number of small setaceous spines is found, 
whether larger ones are present or not. Fruit 9 lines in diameter, with 
a small flat umbilicus. Seeds 2j- lines in diameter. 
* * Articuli tumidi ovati, 
25. O. erinacea, E. &; B. L c. : adscendens ; articulis ovatis seu 
teretiusculis ; pulvillis confertissimis omnibus armatis ; aculeis 5-10 
gracilibus rubellis, 3-5 elongatis ; bacca ovata aculeolata ; seminibus 
magnis subregularibus. 
Near the Mojave, between the Colorado and the Californian moun¬ 
tains. — Joints 2-2^- inches long, 1 - 1^- broad* and thick, some¬ 
times almost cylindrical, densely covered with large white pulvilli, 
which are only 2-3 lines apart. Spines 6-14 or even 20 lines 
long, slender but stiff. Fruit an inch or more in length. Seeds 
nearly 3 lines in diameter. 
26. O. arenaria, E. in B. C. B. : adscendens; articulis -obovatis 
compressis seu teretiusculis tuberculatis; foliis minutis; pulvillis sub- 
confertis pallide setosis ; aculeis 1-4 robustioribus albidis fuscatis- 
ve, cum inferioribus brevioribus 2 - 6 albis; floris sulphurei ovario 
obovato ; petalis emarginatis; stigmatibus 5; bacca oblonga spinulo- 
sa; umbilico infundibuliformi; seminibus magnis irregularibus. 
Sandy bottoms of the Bio Grande near El Paso : fl. May. — 
Spreading 2-3 feet, \ - 1 foot high ; roots stout, creeping horizon¬ 
tally ; joints 1J - 3 inches long, 1-2 inches wide, and | - f thick, 
more strongly tuberculated than the allied species ; leaves only a line 
long; pulvilli 3-5 lines apart, very bristly, especially on the old 
joints; upper spines 9-15 lines long. Flower 2-2J inches in di¬ 
ameter. Fruit about an inch long. Seeds 2^-- 3 lines in diameter. 
This is the only one of our Cactacese on which the Cochenille has 
been found. 
27. O. fragilis, Haw. (Cactus fragilis, Nutt.): subdeeumbens; 
articulis parvis ovatis subcompressis tumidis vel subglobosis vix tu¬ 
berculatis nitide viridibus; foliis minutis ; pulvillis subconfertis magnis 
albo-tomentosis, vix setulosis; aculeorum 1-4 robustiorum summo 
valido angulato fuscato porrecto, ceteris debilioribus pallidioribus pa- 
tulis seu radiantibus; aculeis inferioribus 2-6 gracilibus albis radi- 
antibus ; floribus minoribus; bacca ovata vix spinulosa, umbilico in¬ 
fundibuliformi; seminibus paucis magnis subregularibus. 
/ 6 
