O. Davisii has been considered to be identical with O. twni- 
cata, of which the flowers are unknown. 
Descr. A small much-branched bright-green glabrous 
shrub; branches spreading, joints elongate, slightly nar- 
rowed below, two to three inches long by half an inch 
broad; tubercles low, oblong, one-half to three-quarters of 
an inch long, not well defined, smooth; cushions low, 
rounded, about one-sixth of an inch in diameter, clothed 
with woolly felted hairs; spines four to seven, very un- 
equal, slender and straight, the longest half an inch long, 
bright brown, covered with a deciduous glossy scarious 
sheath, often so loose as to give the spine a considerable 
thickness, the lower-most spine often becomes herbaceous 
green and much thickened, both on the joints and calyx. 
Flowers two and a half inches in diameter. Calyx turbinate, 
nearly two inches long, clothed, like the joints, with 
tubercles and spines. Perianth-segments in about three 
Series pale bronzy green, glistening, outer rounded, sub- 
acute, intermediate oblong, inner obovate-spathulate, acute. 
Stamens very numerous and densely crowded, not half the 
length of the perianth-segments; filaments dark red; 
anthers yellow. Stigma partially exserted beyond the 
anthers, oblong, deeply four-lobed, pink,—J. D. H. 
Fig. 1, Flower cut vertically ; 2, spines; 3, 4, 5, stamens :—all enlarged. 
