101 
13. Cactus micromeris greggii (Engelm.). 
Mamillaria micromeris greggii Engelm. Syn. Cact. 261 (1856), 
Larger (2.5 to 5 em. in diameter) and becoming oblong, with larger 
globose-ovate tubercles (2 to 2.5 min. long), fewer rigid spines all radiant 
(interior 5 to 7 shorter and stouter, 1 to 2 mm, long; the outer 15 to 18. 
3 to 4mm. long), and fruit 1.5 to2 mm. long. (J/l. Cact. Mex. Bound, 
t. 2. figs. 5-8)—Type, Gregg 508 in Herb. Mo. Bot. Gard. 
Mountain ridges near Saltillo, Coahuila, Said by Budd to oceur within 
the southern borders of Pecos County, Tex. 
Specimens examined: COAHUILA (Gregg 508; Palmer of 1880). 
It is a question whether this variety does not merely represent an older aud bet- 
ter developed plant than those upon which the species is based. Mr. Harry I. Budd, 
who has made extensive collections of Texan and Mexican Cacti for the market, 
reports that it is impossible to separate sharply the variety from the species in the 
field, and regards the difference merely as one of age. Unfortunately, only living 
material of the species conld be examined, but its characters seem well sustained ever 
in the most vigorous plants, some of which reach the size of the variety. ‘Through 
this variety the species is brought very near the following: 
14. Cactus bispinus. 
Mamillaria microthele Muhlenpf, Allg. Gart. Zeit. p. 11 (1848), not Lem, (1838). 
Differs trom the last forin (var. gregyit) chietly in its cespitose habit, 
much larger tubercles, and two unusually stout and short central spines 
(fide Engelmann, who examined specimens in Coll, Salm—Dyck). 
Credited to Mexico in general, but said by Budd to occur within the 
southern border of Pecos County, Tex. 
** Central spines present and one or more hooked, 
+ Mostly globose and simple plants (occasionally somewhat cylindrical). 
15. Cactus wrightii (Engelm.) Kuntze, Rev. Gen, Pl. 261 (1891). 
Mamillaria wrightii /ngelm. Syn. Cact. 262 (1856). 
Globose or depressed globose (top-shaped below), 5 to 7.5 em. in 
diameter, simple: tubercles 10 to 12mm. long, with naked axils: radial 
spines 8 to 12, white (the upper dusky-tipped), pubescent, 8 to 12 mm. 
long; central spines mostly 2 (usually side by side and divergent), 
rarely 1 or 3, scarcely longer, hooked and reddish-black: flowers 2.5em, 
long, bright purple: fruit about 2.5 cm. long, somewhat subglobose, 
purple: seeds 1.4 mm long, black and pitted. (ZU. Cact. Mex. Bound. 
t. 8. figs. 1-8)—Type, Wright of 1851 in Herb, Mo. Bot. Gard. 
High plains and rocky places, from the Upper Pecos, east of Santa 
Fé, N. Mex., southward through extreme southwestern Texas (between 
the Pecos and El Paso), and into Chihuahua (near Lake Santa Maria), 
Specimens examined: NEw MExico ( Wrightof 1851); Rusby of 1880): 
also growing in Mo. Bot. Gard. 1893. 
Dr. Engelmann calls attention to the fact that this species is closely allied to the 
Mexican C. zephyranthoides (Schiedw.), but in the absence of material represent- 
ing the latter species no comparison can be made. In descriptions of the Mexican 
species the differently colored flowers and the much longer spines suggest differences 
that an examination of fruit and seed characters may still further emphasize. 
