448 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Only 1 central spine in each areole hooked; radials 
15 to 80.2.2... eee eee cee eee 3. M. grahami. 
More than 1 central hooked in some of the areoles; 
radials 8 to 12......... 2.0... cee eee cece e eee 4, M. wrightti. . 
None of the spines hooked, the centrals usually 1, some- 
times wanting; plants flat-topped, with turbinate 
root and milky juice. 
Radial spines few, 5 to 9, stout, dull-colored......... . 5. M. meiacantha. 
Radials more numerous, 10 to 20, slender, white..... 6. M. heyderi. 
Tubercles grooved on the upper side (in M. macromeris the groove 
wanting in young plants and never reaching the axil); none 
of the spines hooked. 
Central spines none or 1; plants small, subglobose, 2 to5 cm. 
high; radials very numerous, 30 to 50, 5 to 10 mm, 
0 0 7. M. dasyacantha. 
Centrals several, generally 3 or more; plants larger, of various 
shapes; radials various. 
Tubercles large, 12 to 35 mm. long (mostly about 20 mm.); 
plants large, with long spines, 
Flowers rose purple; central spines mostly 4, dark, 
slender but strong, 2 to 5 cm. long; plants 
COSPILOS...... seek cee ee ee ce eee cece 8. M. macromeris. 
Flowers brownish yellow; centrals 2 to 5, light-colored, 
stout, 2 to 3 cm. long (one usually curved 
downward at the tip); plants mostly solitary.. 9. M. scheerii. 
Tubercles smaller, usually less than 12 mm. long; plants 
small, with relatively short and numerous spines. 
Fruit bright red; lower spines deciduous, leaving 
the base of the plant tuberculate with dry 
corky protuberances; spines numerous, white; 
centrals 5 to 9, glaucous, purple-tipped....... 10. M. tuberculosa. 
Fruit green; lower spines rarely deciduous; base of the 
plant little or not at all tuberculate; spines 
numerous, but the centrals mostly darker 
and not quite so numerous (except in M. 
radiosa neomexicana),. 
Stigmas short-mucronate; plants proliferous and 
cespitose; seeds yellowish brown........ ll. M., vivipara. 
Stigmas obtuse; plants sparingly proliferous, 
usually solitary; seeds reddish brown, 
slightly larger...............0..200--0--- 12. M. radiosa, 
The references by Coulter! of Cactus scolymoides and C. echinus to New Mexico 
are probably dependent upon an incorrect determination of Mamillaria scheerii, for 
the former at least; and he does not cite any specimens of the latter species, although 
including it in our range. We have seen no specimens of either species from New 
Mexico. 
1. Mamillaria micromeris Engelm. Proc. Amer. Acad. 3: 260. 1856. 
Type Locatity: ‘‘From El Paso eastward to the San Pedro River,”’ Texas. 
Ranoe: Western Texas and southern New Mexico. 
New Mexico: Sacramento Mountains; Guadalupe Mountains; Capitan Mountains. 
Dry limestone mountains, in the Lower and Upper Sonoran zones. 
‘Contr. U. 8. Nat. Herb. 3: 115, 116. 1896. 
