12.100 Mamillaria 
Plant globular, 3.5 cm, high, 4.7 cm. in diameter, slightly flattened; 
axils naked, wide; tubercles about 7 mm. high, light oxide of chromium 
according to Winsor and Nev^ton' s Water Colors, becoming flattened at bases 
shortly below top, bearing areoles circular to elliptical, 2 to 3 mm. in 
diameter or in length; areoles bearing spines, centrals 3 to 5, usually 4, 
13 mm. long and less, varying in color from light yellow to medium drab 
with brown to dark brown tops or sometimes for nearly outer two-thirds; 
radials about 20, whitish, slightly pectinate, 1 cm. long and less, weaker 
than centrals; flo?/ers sessile, growing in small circle around top of plant 
2 cm. long;;calyx tube light green, short, 5 mm. in diameter at base, widen 
ing slightly; sepals oblanceolate , 1 cm. long, very lignt purple with 
creamy white margins; ovary globular, 2 mm. in diameter; throat 5 mm. deep, 
5.5 mm. wide at top; stamens numerous, attached full length of tl^oat; 
