104 
20. Cactus bocasanus (Poselger). 
Mamillaria bocasana Poselger, Gart. Zeit. 94 (1853). 
Depressed-globose, 2 to 3 em. high: tubercles 8 mm. long, with long 
axillary wool: radial spines 25 to 30, white and capillary, 10 to 25 mm. 
long; central spines 2 to 4, slender and naked (or sli ghtly puberulent), 
the most central one hooked (usually upwards), 15 to 25 mm. long, the 
upper 1 to 3 shorter and straight, all yellow with red tips, the hooked 
oneoften brownish-red nearly to the base: flowers unknown: fruif green, 
about 4 mm. long: seeds cinnamon-brown, oblique, broadly obovate, 
with narrowly ovate basal hilum.—Type unknown, 
San Luis Potosi, so far as known. Poselger says, ‘Texas, auf der 
Seira de Bocas, among rocks,” which station we have been unable to 
locate. 
Specimens examined: SAN Luis Povrost (Uschanzier of 1891): also 
specimens cultivated in Hort. Pfersdorff in 1869; in Mo. Bot. Gard. in 
1891; also growing in Mo. Bot. Gard. 1593. 
The capillary radials give the plant a white-woolly appearance. The younger 
spines at the vertex are erect and tufted. Itresembles C. grahami, but the tubercles 
are much more slender and not thickened at base, all the spines are more slender, 
the central hooked one is more reddish, and the fruit is much shorter. 
21. Cactus eschanzieri, sp. nov. 
{ Depressed-globose, 3 cm. in diameter, simple: tubercles broader at. 
base, 6 to 8 min, long, with naked axils: spines all pubescent; radials 
15 to 20, with dusky tips, the lateral 10 to 12 mm. long, the lower weaker, 
shorter and curved, the upper shorter; solitary central spine reddish, 
slender, somewhat twisted, usually hooked upwards, 15 to 25 min. long: 
flowers red (?): fruit reddish (?), ovate, about 10 mm. long: seeds red- 
dish, oblique-obovate, 1.2 mm. long, pitted, with subventral hilum.— 
Type in Herb. Coulter. ~ 
San Luis Potosi. 
Specimens examined: SAN Lurs Porost (Hschanzier of 1891). 
Resembles C. grahami, but with fewer and more slender pubescent spines, longer 
and less rigid central, more exserted fruit, and much larger reddish and strongly 
pitted seeds with subventral hilum, 
22. Cactus tetrancistrus (lMngelm.). 
Mamillaria tetrancistra Engelm. Am. Jour. Sci, 1. xiv. 337 (1852), in part. 
Mamillaria phellosperma Engelm. Syn. Cact. 262 (1856). 
Cactus phellospermus Kuntze, Rey. Gen. PI. 261 (1891). 
Ovate or ovate-eylindrical, 5 to 25 em. high, 3.5 to 7.5 em. in diame- 
ter, simple or rarely branching at base: tubercles ovate-cylindrical, 8 
to 14 mm. long, with axillary bristle-bearing wool, at length naked: 
radial spines 30 to 60, in two series, the exterior bristle-like, shorter 
and white, the interior stouter, longer and dusky-tipped or purplish; 
central spines 3 or 4, stouter, longer, brown or blackish from a paler 
base, the upper 2 or 3 (10 to 14 mm. long) straight, or one or two or 
even all hooked, the lower stouter and longer (12 to 15 mm.), hooked 
