50 CACTACEJXE. 
often partially prostrate; the cylindric tubular wood is reticulated with short meshes. Joints 
1-21 inches long, less than 1 inch thick, tubercles not more than 4 or 5 lines long ; bristles few 
and rather coarse; spines 12-20 ; the 4 larger ones are somewhat central, 9-12 lines long ; the 
others radiating from 4-9 lines long ; the smaller ones, as in all these Opuntic, hardly vagi- 
nate. Flower described from a withered specimen found attached to a fruit, to which it some- 
what adhered, but perhaps held more by the long intricate spines than by an organic attach- 
ment. Flower 13-13 inches in diameter, apparently yellow, which is uncommon among the 
Cylindric Opuntie; petals about 9 lines long and three broad, stigmata about 2 lines long. 
The fruit is very peculiar, and with the seed, characterizes this species well. The wide umbili- 
cus on the shallow fruit gives it the appearance of a saucer, and the seeds find their place more 
around the edge of the umbilicus than in the body of the fruit. Spines on fruit from 4-10 lines 
long. Seed 2 lines or more in diameter, with a broader commissure than any of the allied 
species, cotyledons always, all the specimens examined regularly accumbent or parallel ; the 
only species, so far, where this regularly is the case, albumen unusually large. 
O. Serpentina, from San Diego, is very nearly allied to our species, but seems sufficiently 
distinct by its elongated cylindric joints and different growth. 
21. O. BrexLovit, Englm.: caule arborescente erecto crasso reticulato-lignoso, ramis erectis 
adscendentibusve numerosis congestis, inferioribus demum refractis, articulis ovatis s. ovato- 
cylindricis tumidis leete s. pallide viridibus fragilibus; tuberculis subhemisphericis depressis 
confertis ; pulvillis immersis ovatis setas pallidas penicillatas et aculeos 6-10 robustiores pal- 
lidos stramineo-vaginatos, 3 deflexos, ceteros divergentes et 6—10 graciliores inferiores radiantes 
gerentibus ; ovario tuberculis plurimis stipato parce aculeolato ; bacca ovata profunde umbili- 
cata tuberculata pulvillos immersos 60—70 setigeros inermes s. aculeolos sub-3 vaginatos وج‎ 
seminibus parvis. —(Plate XIX, fig. 1-7.) 
On Williams' river, a branch of the Colorado; 10-12 feet high, stem $ inch in diameter ; 
skeleton forming a large hollow tube, much walla taq with numerous small roundish or some- 
what rhombic meshes in 13 or 21 spiral rows. Branches forming a dense head ; younger joints 
erect, adpressed very fragile, often shaken off by the wind and covering the soil around, taking 
root everywhere, or sticking to the clothes of the passers-by like burrs. The joints on the older 
part of the stem are often persistent and reflexed, becoming withered and brown. Joints 2-6 
inches long, 1-2 inches in diameter, light fiesh green, covered with the small almost hemi- 
sherical, and not very prominent, tubercles, which are 3—4 lines long, and arranged mostly in 
13 spirals ; the areola is immersed at the apex of the tubercle, and surrounded by an elevated 
paler or almost whitish ridge, having the appearance of 2 lateral glands. Larger spines about 
linch long. Flower or complete fruit not seen ; an ovary or young fruit before me is clavate, 
1 inch long, and has a few spines on the pulvilli some empty (sterile?) fruits brought home 
are oval 13-13 inches long, 1 inch in diameter, strongly tuberculated, and spineless; others 
again are even larger, with more numerous tubercles, and the pulvilli beset with 3-6 sheathed 
spines 4-7 lines long. These are evidently undergoing a change into joints ; proliferous seeds, 
said to be small, but most unfortunately the specimens were lost, so that we were unable to com- 
pare them with those allied species found further south, (O. fulgida,) and on the Pacific coast, 
(O. prolifera.) Our plant is distinguished from these forms by its short >0 immersed 
pulvilli, and large tuberculated and somewhat spiny fruit. 
[I have thought proper to consecrate this remarkable species, so conspicuous in its desert 
wilds, to my colaborer Dr. J. M. Bigelow, through whose intelligent exertions and indefatigable 
n so many new Cactacee, described in this — have been discovered and brought 
home.— M 
22. O. WnrPPLzr, (sp. nov.): caule erecto s. rarius patulo s. subprocumbente, reticulato- 
lignoso, divaricato ramoso, articulis cylindricis ; tuberculis ovatis confertis, pulvillis pulvinatis 
