This extract is the unabridged text referring to the genus Ariocarpus from Cactaceae of the Boundary. Report of the United States and Mexican Boundary Survey, Vol. 2, Senate Ex. Doe, No. 108, Washington, D. C., 1859.

Subgen 3. Anhalonium

These very curious plants, some of them looking more like some Aloe than like a Cactus, can nevertheless not be separated from Mamillaria. The seed is the only part of the organs of fructification which seems to offer any character, by having a hard, roughly tuberculated testa in ours as well as in another Mexican species which I had the opportunity to examine. Our species (and probably all the others) has the flower and fruit sessile upon the lower part of the tubercle and elevated above the axil, much as in M. macrorneris; but, unlike that plant, the lower part of the tubercle is entirely distinct from the upper one.

23. M. FISSURATA (sp. nov.): e radice crassa napiformi simplex, depresso-globosa seu applanata; vertice densissime villoso; tuberculis e basi applanta dilatata crassis triangularibus inermibus extus infraque laevibus seu versus marginem crenulatum rugosis, supra sulco centrali villoso lateralibusque 2 nudis profunde quadripartitis et sulcis transversalibus in tubercula irregularia angulosa numerosa multifidis; floribns e villo longo sericeo centralibus breviter tubulosis; sepalis sub-20, inferioribus lineari-lanceolatis integris carnosis albidis, superioribus spathulatis cuspidatis; petalis sub-12 spathulatis versus apicem obtusum mucronatum integriusculis seu laceris roseis; stigmatibus 5-10 erecto-patulis; baccis ovatis pallide virescentibus in lana densa occultis; seminibus obovato-globosis tuberculatis nigris opacis, hilo basilari transverso; embryone obovato erecto. (Plate XVI.)

(On-screen reproduction of the whole plate does not do justice to the quality of the illustration, two enlargements showing greater detail are available here Fig.1. The plant body, and, Fig.2. Tubercle, areole and seed structure.)

On hard, gravelly, limestone hills, near Fairy Springs, not far from the mouth of the Pecos, and between that river and the San Pedro, Schott, Bigelow; and higher up on the rocks of the canon of the Rio Grande, Parry: fl. September and October.-The lower part of the plant is top-shaped, covered with the scale-like remains of the earlier tubercles; the upper part is hemispherical or depressed and flattened, hardly elevated above the surface of the ground, 2-4.5 inches in diameter ; tubercles in my specimens 6-10 lines long and a little less broad, or sometimes the upper warty part "0.75 inch long and 1.25 inch wide," in 5 or 8, or rarely in 13 spiral rows. Lower part of tubercles flattened, acute at the edges, slightly carinate, more on the upper and less on the lower surface, smooth. Upper and exposed part of tubercle triangular in outline, convex, carinate and almost smooth below, convex and variously fissured arid thereby verrucose above, sharp and crenate on the edges. The principal groove on the upper surface is a longitudinal one corresponding to the groove of the different species of Coryphantha, and like that villose ; towards its base (at the base of the upper or warty part of the tubercle) it expands into the floriferous areola, upwards it ceases just under the acutish point of the tubercle without any trace of an aculeiferous areola or of spines ; in the young tubercle it is coated by dense, long and straight, white or yellowish, silky wool, (about an inch long,) which from being exposed to the weather gets matted and dirty, and after several years entirely disappears. Two lateral grooves run parallel with this, and together with the many transverse fissures cut up the upper surface into numerous angular tubercles or warts. Flowers central or vertical, in the sense of the term as explained before, borne on the lower smooth part of a very young tubercle, which when bearing flower and fruit is somewhat thickened, and takes the shape and functions of a short penduncle, bearing laterally the upper part of the tubercle like a small bract. The axils even of these young tubercles are entirely naked ; the long wool which covers the lower part of the flower, and entirely hides the whole fruit, being produced entirely from the areola and the central groove. Flower about an inch long and of the same diameter when fully open; ovary 3 lines long, oval ; tube 4-6 lines long; 12 exterior sepals, whitish, fleshy, 8 inner ones spathulate, mucronate, with rose-colored edges 6-9 lines long, 2 lines wide; petals about 12 in a single series, 9 lines long, 2 lines wide, rose or pink-colored; stamens numerous, white with orange anthers; style white, expanding into a funnel-shaped irregularly 5-10 parted light-yellow stigma. Fruit oval, crowned with the remains of the flower, about 5 lines long, juicy. Seed 0.8 line long, strongly tuberculated, the transverse and somewhat truncate hilum basilar.