CACTACER. 55 
transverse diameter ; cotyledons in all the seeds examined oblique. Dedicated to one of its 
discoverers, whose name I have often had occasion to mention. 
Dr. Gregg has sent a similar plant from San Luis Potosi, Mexico, which, though growing 7 
or 8 degrees farther south, I must consider the same as O. Schottii. Its joints 2 inches long; tuber- 
cles 10-12 lines long ; 4 central spines ancipital or triangular, 12-20 lines long, much less rough, 
8-12 exterior spines of very different sizes. (Tab. LXXIII, fig. 4.) 
15. O. GRAHAMI (sp. nov.): radicibus crassis fusiformibus ; articulis breviter clavatis adscen- 
dentibus lete viridibus; tuberculis oblongis ; foliie basi ovata abrupte acuminatis ; pulvillis 
albo-tomentosis setas demum numerosas elongatas rigidas gerentibus; aculeis gracilibus scabris 
rubellis demum cinereo-fuscis, interioribus 4-7 robustioribus scabris teretiusculis seu 4-angulatis 
seu rarius compressis, exterioribus 4-6 multo minoribus ; flore flavo; ovarii pulvillis sub 30 
albo-tomentosis setosis; bacca ovata setosissima ; ‘aie eties regularibus vix rostratis, commis- 
sura lineari indistincta. (Tab. LX XII.) 
Sandy soil in the bottom of the Rio Grande, near El Paso, and for a distance of about 100 
miles along the river, Wright, Bigelow ; fl. June.—Roots often 6 inches long and an inch thick, 
tapering, single or divided ; joints 14-2 inches long, } or at most 1 inch in diameter ; tubercles 
6-7 lines long ; leaves similar to those of O. vulgaris, short and thick; nearly a line in diam- 
eter at base and about twice as long. Larger spines 1}-2 inches long and spreading, scabrous, 
slenderer than in any allied species. Flowers apparently 2 inches in diameter, and, like 
the fruit, very similar to those of O. clavata ; seeds 2.5-2.8 lines long, with a linear and often 
very indistinct commissure; cotyledons in the seeds examined regularly incumbent. This 
species, peculiar to an interesting part of our boundary, has been named in honor of the gen- 
tleman who was for a time chief of the scientific corps of the Commission, and by whose orders 
this, with many other species of Cacti, has been sent to me. 
16. O, BULBISPINA (sp. nov.): radicibus fusiformibus ; articulis parvis ovatis vix clavatis seepius 
ex apice proliferis fragilibus ; pulvillis parce setosis, junioribus laxe villosis; aculeis teretius- 
culis scabrellis basi bulbosis, interioribus 4 cruciatis, inferiore longiore, exterioribus 8-12 
radiantibus. (Tab. LX XIII, fig. 5-6.) 
Near Perros Bravos, north of Saltillo, Gregg.—_Spreading masses 2—4 feet in diameter ; joints 
9-12 lines long, 6 lines in diameter, often proliferous at the upper end ; tubercles 3-4 lines 
long ; interior spines 4—6 lines, exterior ones 14-3 lines in length. This species has the sub- 
cylindric joints, the reticulated ligneous texture, and the scabrous spines of the clavate Opuntic, 
but its mode of ramification is rather different, and the form of the joints is more ovate than 
clavate. Perhaps it belongs rather to Prince Salm’s section Glomerate, and near 0. pusilla 
from South America. 
§ 2. Cylindrice. 
Stems ascending or usually erect, much branched ; joints cylindric or tumid, tuberculate or 
sometimes almost smooth ; the ligneous tissue is compact, and either (in spec. 17-24) forms a 
reticulated hollow tube, in which the meshes correspond with the tubercles, and which by age 
becomes more and more solid and massive, or it is (in spec. 25-28) reticulated only when quite 
young, and soon becomes quite dense. The spines are almost always terete, and are always 
covered with a loose glistening sheath, Flowers purple or rarely yellow, large, or usually 
middle sized or (in the two last species) quite small. The fruit is unarmed, somewhat fleshy or 
