Differs from var. deserti in its more robust and branching habit (becoming 12.5 cm. tall and 10 cm. in diameter), shorter and thicker tubercles, more numerous (12 to 14 centrals) stouter and longer (12 to 22 mm.) spines, all of which are black-tipped (the centrals black half way down, shading into red), and pink flowers. Type, Alverson's specimens in Herb. Mo. Bot. Gard. and in Herb. Coulter.

In the desert region of extreme southeastern California.

Specimens examined: Southern California (A. H. Alverson of 1892): also growing in Mo. Bot. Gard. 1893.

The covering of stout bushy interlocking spines is like that of var. deserti, but the black and reddish coloration gives a decidedly different appearance. On account of this appearance of a reddish-black brush the plant has been popularly called "foxtail cactus." The decidedly pink flowers were sent by Mr. S.

B. Parish from specimens growing in cultivation in San Diego, and are not from the original collection of Mr. Alverson.

64. Cactus macromeris (Engelm.) Kuntze Rev. Gen. Pl. 260 (1891).

Mamillaria macromeris Engelm. Wisliz. Rep. 13 (1848).

Mamillaria heteromorpha Scheer in Salm. Cact. Hort. Dyck. 128 (1850).

Mamillaria dactylithele Labouret, Monogr. Cact. 146 (1858).

Ovate or cylindrical, 5 to 10 cm. high, simple or branching from the base and at length cespitose: tubercles large, loose and spreading, from a dilated base, more or less elongated (12 to 30 mm.) and teretish (often incurved), the groove absent in young plants and never reaching the axil: radial spines 10 to 17, slender and terete, or stouter and often angled, spreading, 12 to 40 mm. long, whitish (or more or less rose-colored when young), straight or a little curved; central spines 4 (or fewer in young plants or even wanting), spreading, 25 to 55 mm. long, stouter, bulbous at base, mostly black (the lowest the longest and stoutest), straight or sometimes curved or twisted: flowers 6 to 7.5 cm. long and of same diameter, deep red to purple: fruit ovate-subglobose, green, 15 to 25 mm, long: seeds globose-obovate, yellow, and smooth. 1.2 to 1.6 mm. long. (Ill.

Cact. Mex. Bound. t. 14 and 15) Type, Wislizenus of 1846 in Herb. Mo. Bot. Gard.

Mostly in loose sand, in the valley of the Rio Grande (on both sides of the river), from southern New Mexico to Eagle Pa.s.s, Texas, and doubtless further down.

Specimens examined: New Mexico (Wislizenus of 1846; Wright 384, 531, of 1852; G. R. Vasey of 1881): Texas (Wright of 1850, 1851, 1852; Bigelow of 1852): Chihuahua (Evans of 1891; Budd of 1891): also growing in Mo. Bot. Gard. 1893.

This species shows an interesting transition from Coryphantha to Echinocactus. The woolly groove of the Coryphantha extends from the spine-bearing areola to the axil of the tubercle, where it expands into the flower-bearing areola. In C. macromeris the groove extends only about half way down the tubercle and gives origin to the flower-bearing areola on the side of the tubercle; while in Echinocactus the flower-bearing areola becomes adjacent to the spine-bearing areola and the flower appears at the summit of the tubercle.

ARTIFICIAL KEY TO THE SPECIES.

It seems impossible to make a simple artificial key that will serve as a useful guide to each individual species and variety.

Our knowledge of so many of the species is imperfect, that no set of characters can be applied throughout. However, as no plants are collected in such fragmentary condition, it will be useful to construct a key based upon such characters as are always likely to be present, even if specific distinctions are not always reached. In many cases, species are so closely and differently related to each other that the complete descriptions will have to be consulted to determine the differences, and in such cases the artificial key can only indicate the group. Even the full descriptions are very compact, all characters not necessary for discrimination having been eliminated. No attempt need be made to determine any species by means of the flowers alone. In most cases more or less of the plant body will be available, presenting spine and tubercle characters, and these are used in the following key. The distinction between Eumamillaria and Coryphantha, on the basis of grooveless and grooved tubercles should always be made out easily. It may be useful to suggest as a caution, however, that often tubercles in drying develop folds which simulate grooves, and especially is this true in quadrangular tubercles. In such cases it is necessary to restore the original plumpness of the tubercle by boiling, before the presence or absence of the groove can be definitely determined.

The species and varieties are indicated only by their specific or varietal names in the following key, and the numbers refer to the serial numbers of the synoptical presentation. Forms occurring within the United States are marked with an "*":

I. Tubercles never grooved.

* Central spines none.

Radials 5 to 9, stout.

meiacanthus* (7).

Radials 20 to 40.

micromeris* (12), greggii (13).

Radials 40 to 80.

lasiacanthus* (10), denudatus* (11).

** Central spine solitary and not hooked.

+ Central spine longer than the radials.

Radials 7 or 8: tubercles very long (40 to 50 mm.).

longimamma (36).

Radials 15 to 20: tubercles 6 to 8 mm. long.

eschanzieri (21).

++ Central spine shorter than the radials.

Radials 5 to 9, stout.

meiacanthus* (7).

Radials 9 to 22.

heyderi* (5), hemisphaericus* (6), gummiferus (8), gabbii (34), sphaericus (35).

*** Central spine solitary and hooked.

+ Stems slender cylindric: Lower Californian.

Centrals 1, 20 to 30 mm. long.

rosea.n.u.s (23).

Centrals 1 to 4, 20 to 50 mm. long.

setispinus (24).

++ Stems depressed-globose to ovate.

Radials 4 to 6, rigid.

uncinatus (9).

Radials 8 to 12.

wrightii* (15).

Radials 15 to 30.

grahami* (19), eschanzieri (21).

Radials 50 to 60.

barbatus (18).

**** Central spines more than one, and none of them hooked.

+ Slender or sometimes stout cylindrical plants, branching at base: Lower Californian.

brandegei (3), setispinus (24), halei (25).

++ Depressed-globose to ovate and stout cylindrical.

++ Radials few (3 to 12) and rigid: Mexican.

Radials 3: centrals 3.

alternatus (1)