24 Proceedings of the Biologiccd Society of Washington. 
spicules, 1 mill, long tiiul 1 to o long, delicate reddish-brown fugacious 
spines, 1 to 2 nun. in length and sheathed at their tips only, and 2 to 3 
delicate, fugacious, shorter, lighter c<)lored unsheathed bristles beside; 
seeds white, typical of the group, and 3 mm. in diameter. 
This species belongs to the Op. arborescens group. The type is pre¬ 
served under my inventory No. 8152, which was grown Irom cuttings 
secured near Torreon, Mexico, September 24. 1005. 
Opuntia spinotecta sp. nov. 
An arborescent, divaricately Iiranched, cylindrical jointed species, 
2K oi. bigh, with trunks 10 to 12 cm. in diameter, commonly compactly, 
but in age openly branched, and having thick fusiform, tuberous roots; 
joints variable, but mostly 10 to 15 cm. long, but often 40 cm. in length, 
somewhat clavate, the tubercles 1 cm. higb, with npjier crest lialf the 
length of the lower and a darker green line surrounding the entire 
tubercle; areoles occupying upper crest of tubercles, broadly obovate, 3 
to 4 mm. long, tawny, turning to dirty gray or black, but with new 
tawny wool appearing in upper part of areole for two years or more; 
leaves cylindrical, subulate, cuspidate, 1 cm. long; spicules white, not 
conspicuous on either joint or fruit; spines 3 to (i, mostly 4, the upper 
central the longest, about 3 cm. long and loosely sheathed, the lower 
lateral ones losing their sheathes early, flesh-colored or brown, with 
white papery sheathes; flowers purple; fruit obovate- to subglobose, 
yellowish-green, persistent. 
The type bears my inventory No. 9859, collected at Durango, INIexico, 
September, 1909. The description was drawn mainly in the type 
locality. The plant has been in cultivation since the date of collection. 
Opuntia valida sp. nov. 
An erect to ascending, widely radiating branched species, with main 
limbs ascending or horizontal, and sometimes resting on edge under cul¬ 
tivation, but mostly erect to ascending in natural habitat, 1 m. iu height 
and 2 m. in spread of branch; joints obovate, large, thick, glaucous, 
slightly blue-green, very broadly pointed or rounded above, commonly 
25 by 32 cm. or again 25 by 27 cm., 1 joint on ])lants in cultivation, .30 
by 42 cm. which is unusual; areoles very large, ovate, 8 mm. long on 
sides of joints and on edges subcircular, 9 to 11 mm. iu diameter, at 
flrst brown, turning almost black, liually gray, the wool prominent, 
mostly elevated 1 or 2 mm. above surface of joint especially on the 
edges, spicules scattered, not numerous, from 2 mm. long on sides to 1 
cm. long on edges of joints, commonly only aliout 25, increasing in age, 
but always scattered through entire areole, although at first appear¬ 
ing on its upper half, stout and faintly annular; spines bright deep 
reddish-lirown at base, fading gradually to a semi-trausluceut bone-like 
tip, and iu age becoming gray, flattened on upper side, faintly annular, 
sometimes slightly twisted, diverging in all directions, 2 to 5 strongly 
