OF ARTS AND SCIENCES. 269 



culis teretibus laxis leviter sulcatis ; axillis subvillosis ; aculeis rectis 

 tenuibus setaceis patulis, exterioribus 25-35 albidis, interioribus 7 - 13 

 longioribus purpureo-fuscis, centrali infero requilongo ; baccis cen- 

 tralibus ovatis ; seminibus obovato-globosis nigricantibus scrobiculatis. 

 El Paso and eastward. — Specimens before me are 1 J - 2^ inches 

 high, and a little less in diameter ; tubercles 4-5 lines long ; spines 

 more slender and soft than in the allied species, often capillary, 

 spreading, but not radiating, 6-12 lines long, only the lower exterior 

 ones a little shorter. Seeds about half a line long. Very nearly 

 allied to the next. 



28. M. viviPARA, Haw. : simplex s. cfespitosa ; tuberculis teretibus 

 laxis leviter sulcatis ; aculeis rectis rigidis, exterioribus patentissime 

 radiantibus albidis 12-36, centralibus 3-12 robustioribus longiori- 

 bus obscurioribus, singulo robustiore porrecto deflexove, ceteris sur- 

 sum divergentibus ; floribus subcentralibus purpureis magnis ; baccis 

 sublateralibus ovatis viridibus ; seminibus obovatis scrobiculatis fulvis. 



Var. a. VERA : depresso-globosa, simplex s. plerumque prolifera, 

 csespitosa; aculeis radialibus 14-20, centralibus 3-8. 



Var. ? |3. RADiosA : ovata s. subcylindrica, simplex s. e basi ramosa ; 

 aculeis radialibus 12-36, centralibus 3-12. Subvar. a. radiosa 

 BOREALis : subglobosa ; aculeis radialibus albidis 12 - 20, centralibus 

 3-6 purpureo-maculatis ; floribus minoribus. — h. radiosa Neo- 

 Mexicana : ovata ; aculeis radialibus albidis 20 - 36, centralibus 

 3-12 supra purpurascentibus sphacelatis ; floribus majoribus. — 

 c. RADIOSA Texana : ovato-cylindrica ; aculeis radialibus albidis 20- 

 30, centralibus 4-5 flavis s. fulvis ; floribus seminibusque magnis. 

 M. radiosa, E. in Plant. Lindh. 2. 1850. 



In the Western plains, and on the Rocky Mountains : var. a. on the 

 Upper Missouri and Yellowstone Rivers ; /3. a. in Northern New Mex- 

 ico ; (3. b. from Western Texas to New Mexico and Sonora ; )3. c. in 

 Texas, west of New Braunfels. — The extreme forms are certainly 

 very unlike one another, but the transitions are so gradual that I cannot 

 draw strict limits between them. Even the proliferous growth of the 

 original M. vivipara is not constant, and I have seen many simple 

 specimens from the Upper Missouri. The simple ones seem to flower 

 better than the proliferous ones, which are often sterile. — Plants from 

 1 to 5 inches high, 1^-2 inches in diameter ; tubercles 4-6 lines 

 long; spines always rigid, 3-10 lines long. Flowers different in 

 size, 12^-2^ inches in diameter, beautifully purple, with numerous 

 narrowly lanceolate acuminate petals. Seeds | - 1 line long. 



