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just behind the apex to mark its upper extremity. This apical areola, therefore, does 
not represent a spine-bearing areola, but the closed upper extremity of a tubercle 
groove. 
It seems evident that Anhalonium is a much modified Cactus, and that its affinity 
is with the coryphauths, through such a species as C, macromeris, in which the flower 
becomes extra-axillary. If in macromeris, with the flower standing well up on the 
tubercle, the portions of the tubercle above and below the flower should become very 
different from each other, the upper portion being so much modified as to cause the 
spine-bearing areola to be obliterated, the condition of things in Anhalonium would 
be obtained. 
* Upper surface of tubercle with a broad and deep wool-bearing longitudinal groove which 
widens below. 
1. Anhalonium engelmanni Lem. Cact. 42 (1839). 
Mamillaria fissurata Engelm, Syn. Cact. 270 (1856). 
Anhalonium fissuratum Engelm. Bot. Mex. Bound. 75 (1859). 
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 
em. 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. FI. 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. suleatum 
Salm-Dyck), but unfortunately notype 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 in 4. kotchubeyi, aside from the central furrow, is 
smooth; at least the margin is ‘ very entire.” 
* * Upper surface of tubercle not grooved, but usually with a tomentose pulvillus at the 
tip. * 
2. Anhalonium prismaticum Lem. Cact. 1 (1839). 
Mamillaria prismatica Lem. Hort, Univ. i. 231 (1839), 
Cactus prismaticus Kuntze, Rev. Gen. Pl. 261 (1891). 
Flat above, top-shaped below, 7.5 to 12.5 cm. in diameter: tubercles 
(upper portion) closely imbricate but squarrose-spreading, sharply tri- 
angular-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 
