The tubercles are so close together that the plant appears thickly covered with the unusually stout and erect-spreading straight spines, a few of the centrals being specially prominent.

The plant is more slender than the ordinary "cylindrical"

members of the genus, but stouter than the slender hooked forms of the preceding section.

26. Cactus rhodanthus (Link & Otto) Kuntze, Rev. Gen. Pl. 261 (1891).

Mamillaria rhodantha Link & Otto, Icon. t. 26 (1828-31) Mamillaria lanifera Haw. Phil. Mag. lxiii., 41 (), not Salm-Dyck (1850).

Oblong or subcylindric, 30 cm. or more high, 7.5 to 10 cm. in diameter, often forking from the middle: tubercles conical, 12 mm. long, 8 mm. in diameter, with woolly axils: radial spines 16 to 20, bristle-like, white, the lower longer (8 to 10 mm.); central spines 6 or 7, rigid, whitish with black tip, 12 mm.

long: flowers rose color, 12 mm. in diameter: fruit 2.5 cm. long, cylindrical. (Ill. l. c.) Type unknown.

Referred to Mexico in general, but reported as yet from San Luis Potosi to southern Mexico. Fl. profusely all summer.

Specimens examined: San Luis Potosi (Bourgeau 47; Pringle 3679; Eschanzier of 1891): also growing in Mo. Bot. Gard. 1893.

The specimens of Bourgeau and Pringle have somewhat larger spines than the type, as indicated by the description.

27. Cactus rhodanthus sulphureospinus.

Mamillaria sulphurea Forst. Handb. Cact. (1846), not Cactus sulphureus Gill, (1830).

Mamillaria rhodantha sulphurea Salm, Hurt. Cact. Dyck. 11 (1850).

Central spines sulphur-yellow; otherwise like the species. Type unknown.

San Luis Potosi.

Specimens examined: San Luis Potosi (Pfeiffer, with no number or date; Eschanzier of 1891).

The varietal distinction maintained seems a small one, but it is constant and striking, so far as can be discovered.

28. Cactus capillaris.

Mamillaria lanifera Salm, Cact. Hort. Dyck. 98 (1850), not Haw.

Cactus laniferus Kuntze, Rev. Gen. Pl. 250 (1891).

Cylindrical and erect: tubercles crowded, conical, glaucous, with axillary bristles: radial spines capillary and very numerous, white and crisped, entirely covering the plant; central spines 4 to 6, rigid, straight and spreading, straw-colored, 8 to 12 mm.

long: flowers equaling the tubercles, the yellow petals striped with red: fruit unknown. Type unknown.

Referred to Mexico in general, but definitely known only from Coahuila.

Specimens examined: Coahuila. (Palmer of 1880).

There is a confusion of synonymy between this species and C.

rhodanthus, both having been named Mamillaria lanifera. The earlier M. lanifera of Haworth, however, is clearly M. rhodantha of Link & Otto; and although Prince Salm-Dyck revived the name for the present species, the law of h.o.m.onyms will not permit it to stand. The name proposed refers to the abundant display of capillary radial spines, which is probably the most notable feature.

29. Cactus palmeri, sp. nov.

Cylindrical: tubercles crowded, glaucous, cylindrical (somewhat broadest above), about 4 mm. long, with dense axillary wool containing bristles: radial spines 25 to 30, very slender and white but rigid, about 5 mm. long, spreading or somewhat radiant, entangled with those of neighboring tubercles, and so covering the whole plant; central spines 3 to 5 (usually 4), more robust, erect or slightly divergent, brownish with darker tip, 7 to 8 mm.

long: flowers small: fruit clavate and scarlet: seeds black and strongly pitted, 0.5 to 0.8 mm. in diameter. Type, Palmer 921 in U. S. Nat. Herb.

San Benito Island, off the west coast of lower California.

Specimens examined: Lower California, San Benito Island (Palmer 921 of 1889, reported as Mamillaria Goodrichii).

Very closely allied to C. capillaris of eastern Mexico.

30. Cactus stellatus Willd. Enum. Suppl. 30 (1813).

Cactus pusillus DC. Cat. Hort. Monsp. 184 (1813), not Haw.

(1803).

Mamillaria pusilla DC. Prod. iii. 459 (1828).

A very common West Indian species, apparently differing from the variety only in the very much fewer (12 to 20) radial spines, although numerous specimens, both dried and living, were examined for additional characters. This difference, however, is so constant and striking that, taken together with the wide geographical separation, it should stand as varietal.

31. Cactus stellatus texa.n.u.s (Engelm.).

Mamillaria pusilla texana Engelm. Syn. Cact. 216 (1856).

Mamillaria texana Young, Fl. Texas, 279 (1873).

Ovate-globose, 2.5 to 3 cm. in diameter, 2.5 to 6 cm. high, proliferous and at length cespitose: tubercles 7 to 9 mm. long, the long axillary wool intermixed with several coa.r.s.e twisted bristles: radial spines very numerous, in many series, the outer ones (30 to 50) capillary, white, elongated and flexuous or crisped (12 to 16 mm, long when straightened), the inner ones (10 to 12) more rigid, shorter (6 to 8 mm.), p.u.b.erulent, whitish or yellowish, usually dark-tipped; central spines 5 to 8, rigid, straight, p.u.b.escent, unequal, white below and reddish or dark above: flowers 1.5 to 2 cm. long, the yellowish-white petals with reddish median band: fruit 1.5 to 2 cm. long: seeds black and shining, conspicuously pitted, 1.2 mm. long. (Ill. Cact. Mex.

Bound. t 5.) Type, Bigelow specimens in Herb. Mo. Bot. Gard.

From the mouth of the Rio Grande to El Paso, Tex., and southward into Coahuila and Chihuahua. Fl. March-May.

Specimens examined: Texas (Bigelow of 1853; Nealley of 1892): Coahuila (Bigelow of 1853): also growing in Mo. Bot. Gard. 1892 and 1893.

The exterior capillary spines cover the whole plant as with a coa.r.s.e wool.

32. Cactus pringlei, sp. nov.

Globose (?), 5 cm. in diameter: tubercles short-conical, about 6 mm. long, with very woolly axils: radial spines 18 to 20, setaceous-bristly and radiant, 5 to 8 m in. long; central spines 5 to 7 (usually 6), stout and h.o.r.n.y, more or less recurved, spreading, 20 to 25 mm. long; all straw-colored, but the centrals darker: flowers deep red (darker, even brownish, outside), 8 to 10 mm. long: fruit unknown. Type, Pringle of 1891 in Herb. Gray.

San Luis Potosi.

Specimens examined: San Luis Potosi (Pringle of 1891).

Evidently a member of the Chrysacantha group and near C.

rhodanthus sulphureospinus, but differs in the much shorter tubercles, straw-colored spines, shorter radials, much longer centrals, and smaller darker flowers.

33. Cactus sphaerotrichus (Lem.) Kuntze, Rev. Gen. Pl. 261 (1891).

Mamillaria sphaerotricha Lem. Cact. 33 (1839).

Depressed-globose: tubercles cylindrical, obtuse, with some axillary bristles: radial spines very much crowded, exceedingly numerous, radiant, very slender and bristle-like, white; central spines 6 to 10 and even more, erect and more rigid: flowers pale reddish: fruit unknown. Type unknown.

Referred to Mexico in general, but reported only from San Luis Potosi.

Specimens examined: Mexican specimens from Hort. Dyck in 1857; from Hort. Pfersdorff in 1869; and growing in Mo. Bot. Gard. 1893 (from material sent by Pringle from San Luis Potosi).

++ The single central spine shorter than the radials (in C.