34 MISSOURI BOTANICAL GARDEN. 
arated areas upon the highland of Mexico, especially in-the 
vicinity of San Luis Potosi, Mexico, where I have studied 
them at various times for the past six years. In cultivation 
in Texas, it has been exceedingly difficult to propagate Opun- 
tia tunicata, but this one grows readily. Neither has yet 
flowered under cultivation in Texas. 
The description is a compilation of four sets of notes, three 
taken in the type locality and one from cultivated plants, four 
of which from two importations are now growing. The type 
specimen is number 9719 D. G., collected near San Luis 
Potosi, Mexico, August 10, 1904. The name is one com- 
monly applied to both species in this region, and arises from 
the fancied resemblance of these plants to small dogs, in 
attacking the feet of pedestrians.—Plates 13 and 14. 
Opuntia tardospina, sp. nov. 
A robust, rapid-growing, spreading to half-prostrate species, about 
one meter or less in height; joints subcircularto broadly ovate or even 
obovate, often 24 X 30cm., but usually smaller although in about same 
proportion, glaucous when young but brighter more yellowish green 
later, this year’s growth about 1 cm. thick and not increasing much 
in age; areoles very prominent, obovate to subcircular, about 4 5 
mm. when young enlarging with age to about 1 em. in diameter and 
elevated 3 or 4 mm. by protrusion of the abundant wool, brown at first 
but soon turning black or dirty gray, 3 or4cm. apart; spicules light 
brown proximally and yellow distally and remaining this way or fading 
to yellow throughout, scattered but more numerous above, unequal, 
often 12 to 15 mm. long, increasing with age, very stout and formid- 
able, diverging in all directions from the hemispherical areole; spines 
mostly on old wood, only an occasional one 2 to 8 em. long in an 
occasional areole on current year’s growth, yellow or brown at base 
only, very faintly if at all annular, not twisted, mostly tightly re- 
curved or simply sloping downward; fruit broadly obovate to pyriform, 
about 45.5 em., having small subcircular black areoles bearing a 
small tuft of spicules like the stem, about 15 mm. apart. 
The species is very different from any known to me. The 
spicules are very long, numerous and prominent, sometimes 
covering the old stems, much like those of Opuntia chlorotica 
santarita. Sometimes the spines become 2 to 4 em. long, but 
this is rare. This applies to the plant growing in its natural 
habitat. When under the more favorable conditions of culti- 
