CACTACES. 59 
dilatatis (sterilibus ?) ; stigmatibus 7-8 erectis ; bacca ovata plane umbilicata pulvillis magnis 
albo-tomentosis inermibus notata ; seminibus parvis angulatis vix rostratis anguste commissu- 
ratis valde compressis. (Tab. LXXV, fig. 19.) 
South range of the Sierra Bubuquibari, in Sonora, and southeastward, in fertile valleys, 
Schott: fl. July and August.—This peculiar species is more tree-like than any other Sonorian 
Opuntia. It has a distinct trunk and a dense top, much ‘like any other ordinary tree, though 
only 5 or 6 feet high; the joints are 3 or 4 inches long, and 1} inch in diameter; the swelling 
tubercles much resemble those of a Mamillaria, whence the name ; the thick leaves are scarcely 
a line long ; spines few, 3-9 lines long, sometimes almost wanting. The flowers are hardly an 
inch in diameter, and of a bright pink or purple color; the ovary is 8 or 9 lines long, and the 
fruit of the same length, slightly tuberculate, in all the specimens before me unarmed, (accord- 
ing to Mr. Schott’s notes, ‘“‘spiny.’’) Seeds 1-1} line in each dimension, often higher than 
broad, very irregular, remarkably similar to those of O. fulgida, but scarcely beaked, and still 
more compressed ; cotyledons incumbent, or often somewhat oblique. 
24. O. Tuurpert (sp. nov.): frutescens, erecta ; articulis cylindricis gracilioribus tuberculatis ; 
tuberculis oblongo-linearibus minus prominulis; pulvillis sub-orbiculatis breviter fulvo-to- 
mentosis vix setosis; aculeis 3-5 brevibus obscuris stramineo-seu fulvo-vaginatis lateraliter 
divergentibus, infimo robustiore deflexo; flore miniato; ovarii clavati tuberculati pulvillis 
18-20 tomentosis brevissime setosis et parce aculeolatis; sepalis tubi obovatis cuspidatis ; 
petalis erectiusculis obovato-spathulatis obtusis retusisve; stigmatibus 7 brevibus crassis erectis. 
Near Bacuachi, Sonora, G. Thurber ; fl. in June.—Similar in some respects to O, arborescens ; 
but the slender joints only about 6 lines in diameter; tubercles 9 lines long, spines 3-8 lines 
long, the lowest one the stoutest! and deflexed. The ovary is about 10 lines long and bears 
on some of the pulvilli 1 or 2 spines, which are evidently deciduous, as we see them in OQ. arbor- 
escens and O. Whipplei; the flower is 14 inch in diameter, dull brick red, salver form, and 
opens much less than that of O. arborescens, which is pure purple ; stigmata 1-1} line long. 
This species I have named for its discoverer, Mr. George Thurber, who, in Mr. Commissioner 
Bartlett’s party, traversed Sonora,and gathered many interesting plants in that then almost 
unknown country. 
25. O. Wricutt (sp. nov.): caule frutescente erecto, juniore reticulate, seniore compacto- 
lignoso ; ramis adscenJentibus ; articulis cylindricis gracilibus sub-tuberculatis ; tuberculis 
elongatis depressis; foliis elongatis subulatis patulis ; pulvillis orbiculatis albo-tomentosis setas 
gracillimas penicillatas gerentibus; aculeis singulis (seu rarius 1-2 superioribus minoribus 
adjectis) porrectis seu paullo deflexis e cinereo rubellis vagina straminea decidua indusiatis ; 
flore miniato; ovarii obovati pulvillis 15-18 albo-tomentosis setosisque; sepalis tubi 9-12 
orbiculatis, exterioribus cuspidatis, interioribus obtusis ; petalis sub-8 late obovatis emarginatis; 
styli crassi stigmatibus 6-7 brevibus adpressis. 
Common on steep rocky mountain sides on the Limpia, Wright, and along the Rio Grande 
from Presidio del Norte to the Pecos, Parry, Bigelow ; also southward, in Mexico, Gregg: fl, 
June and July.—A shrub, 2-4 feet high, about 1 or 1} inch thick below, intermediate be- 
tween Q. arborescens and O. frutescens in size, structure of stem, and arrangement of spines ; 
branches few ; joints 4 lines in diameter; tubercles flat, 7-9 lines long; leaves about 5 lines 
long ; spines 8-10 lines in length, generally single or with 1 or 2 small and divergent ones 
above; in one specimen before me those upper spines are almost as stout and long as the lower 
one; flowers about 1 or 1} inch in diameter; ovary 7-8 lines long} fruib unknuwn.—This 
