but instead of being free and projecting, they lie flat, and are 
adnate to the ridge of the mammilla. This double series 
resembles curiously a wood-louse, with which insects the plant 
seems covered, and which fact has given it the trivial name 
of asellvformis. 
Descr. Stem tufted, dark green, shortly cylindric, three to 
four inches high, one and a half to two inches in diameter, 
often constricted about the middle, apex rounded. Muammille 
spirally arranged, vertical, one third of an inch long, 
_ rhomboidal in a tranverse section at the middle, com- 
pressed laterally at the crown into a ridge, and contracted 
to a narrow base, woolly in the axils; spines minute, short, 
flat, cartilaginous, linear, oblique, subfalcate, pungent, bifari- 
ously arranged onthe crest of the mammilla, adnateto its surface 
with free tips. Howers clustered towards the top of the stem, 
one and a half inch in diameter, sessile. Ovary small, naked, 
oblong, sunk in the axils of the mammille. Perianth-tubeshort, 
free, naked, funnel-shaped ; Segments in about four series, — 
obovate-oblong ; acute, rose-purple. Svamens very numerous, 
inserted in the mouth of the tube, filaments slender, multi- 
seriate ; anthers minute. Style columnar ; stigmas with four 
erect lobes.—J. D. H. | 
Fig. 1, frontand 2, side view of a mammilla ; 3, flower laid open :— 
all magnified. 
