Depressed globose or flat, top-shaped below and tapering into a thick root, 5 to 12 cm. in diameter: tubercles (upper portion) appressed-imbricate, 12 to 18 mm. long and about as wide at base, the upper surface convex and variously fissured (presenting an irregular warty appearance) even to the edges: flowers apparently central, about 2.5 cm. long and broad, shading from whitish to rose: fruit oval, pale green, about 10 mm. long: seeds 1.6 mm. long. (Ill. Bot. Mex. Bound. t. 16)Type unknown; but specimens of Wright, Bigelow, and Parry in Herb. Mo. Bot. Gard. are the basis of Engelmann's Mamillaria fissurata.

On limestone hills, in the "Great Bend" region of the Rio Grande in Texas, and southward into Coahuila.Fl. September-October.

Specimens examined: Texas (Wright of 1850; Bigelow of 1852; Parry, with no number or date; Lloyd of 1890; Evans of 1891; Briggs of 1892): also growing in Mo. Bot. Gard. 1893.

This species is very closely related to the Mexican A. kotchubeyi Lem. (A. sulcatum Salm-Dyck), but unfortunately no type of that species seems to be in existence, and Dr. Engelmann notes (Mex. Bound. Rep. 75) that "it seems no living or dead specimen is at present extant in Europe."Judging from the description, the upper surface of the tubercles inA.kotchubeyi, aside from the central furrow, is smooth; at least the margin is "very entire."Upper surface of tubercle not grooved, but usually with atomentose pulvillus at the tip.

2.Anhalonium prismaticumLem. Cact. 1 (1839).

Mamillaria prismaticaLem. Hort. Univ. i. 231 (1839).Cactus prismaticusKuntze, Rev. Gen. Pl. 261 (1891).

Flat above, top-shaped below, 7.5 to 12.5 cm. in diameter: tubercles (upper portion) close]y imbricate but squarrose- spreading, sharply triangular-pyramidal and very acute (with a sharp cartilaginous tip, which usually disappears with age and leaves the older tubercles blunt or retuse), 18 to 25 mm. long and about as wide at base, the upper surface almost plane and smooth, except that it is more or less pulverulent and usually bears a small tomentose pulvillus (often evanescent later) just behind the claw-like tip: flowers rose-color: fruit elongated- oval and reddish. (Ill. Lem. Cact. t. 1.)Type unknown.

Referred to Mexico in general, but reported definitely only from SanLuis Potosi.Undoubtedly found in Coahuila, and possibly crosses the Rio Grande in the region of the "Great Bend."Specimens examined: San Luis Potosi (Eschanzier of 1891): Mexico in general (specimens from Coll. Salm-Dyck in 1858; Schott of 1858): also specimens cultivated in Mo. Bot. Gard. in 1881; also growing in same garden in 1893.

3.Anhalonium furfuraceum(Watson).

Mamillaria furfuraceaWatson, Proc. Amer. Acad. xxv. 150 (1890).

Very closely related to prismaticum; but triangular portion of tubercle acuminate and shorter, having an irregularly mamillate upper surface, and the acumination ending abruptly in a cartilaginous depression containing a tomentose pulvillus: flowers 2.5 to 3 cm. long, white or pinkish, the sepals brownish. Type, Pringle 2580 in Gray Herb.

At Carneros Pass, Coahuila.

Specimens examined: Coahuila (Pringle 2580 of 1889).

The type of this species was not among the collections received from Cambridge, but a specimen of the same distribution from the National Herbarium shows tubercle dimensions different from those recorded in Dr. Watson's description.In that description the triangular terminal surface is said to be "about an inch broad by one-half inch," which is decidedly different from the equilateral surface of the tubercle of prismaticum.In the National Herbarium specimen of furfuraceum, however, of the same distribution, the surface is almost equilateral, measuring 15 mm. long by 18 mm. wide at base.Without the acuminate upper portion the breadth of the triangular portion would be about double its length.The lower rim of the cup-like depression which terminates the tubercle and contains the pulvillus is sometimes slightly prolonged into a tooth, which in prismaticum becomes the sharp tip of the tubercle.The "minutely furfuraceous-punctulate" character of the tubercle is common to all the species of Anhalonium I have seen, and simply represents the external openings of the remarkably long cuticular passageways to the stomata.

4.Anhalonium pulvilligerumLem. Cact. (1839).

Anhalonium elongatumSalm-Dyck (1850).

This seems to be a third grooveless Mexican species.I have seen nospecimens, but judge from the description that it differs from the two preceding species chiefly in its less crowded and more elongated tubercles (triangular portion 5 cm. long by 2.5 cm. broad at base), which are covered at apex with a tomentose pulvillus.