OF ARTS AND SCIENCES. 



309 



inches thick. Joints 4 lines in dianneter ; tubercles depressed, 7-9 

 lines long; spines 8- 10 lines long. Flower about 1 - 1^. inches in 

 diameter. 



47. O. ARBUSCULA, E. 1. c. : arborescens, erecta, capitato-ramosis- 

 sima ; articulis Isete viridibus elongato-subtuberculatis ; aculeis sub- 

 singulis porrectis vel subdeflexis ; flore flavo-virescente. 



On the Lower Gila, near Maricopa village : fl. June. — A truly 

 arborescent form, with a solid trunk of 4 or 5 inches in diameter, 7- 

 8 feet high ; joints 2-3 inches long, about 4 lines in diameter ; tu- 

 bercles indistinct, about 6 lines long; spine 9-12 lines long, often 

 with 1 or 2 smaller ones under it. Flower li inches in diameter. 



48. O. VAGINATA, E. in Wisl. Rep. (partim) : frutescens, erecta ; 

 ramis erectiusculis ; articulis subtuberculatis ; aculeis subsingulis ; 

 bacca obovata tuberculata coccinea. 



Albuquerque, New Mexico, and southward. — Shrub 3-5 feet 

 high, 1-1^ inches thick ; joints 3-4 lines in diameter ; tubercles 

 rather distinct, 6-9 lines long. Fruit 8-9 lines long. Seed about 



2 lines in diameter. Perhaps a stout form of the next species. 



49. O. FRUTESCENS, E. in PL Lindh. 1845 : frutescens, erecta ; ra- 

 mis erectiusculis ; articulis teretibus ; aculeis subsingulis ; flore parvo 

 virescente ; bacca obovata baud tuberculata coccinea. 



Var. a. LONGispiNA : articulis nascentibus stipitatis ; aculeis validi- 

 oribus longioribus laxe vaginatis. 



Var. /3. BREvispiNA : articulis nascentibus sessilibus ; aculeis graci- 

 lioribus brevioribus arete vaginatis. 



From the Colorado of Texas to Matamoras and Saltillo, westward 

 to Sonora and the Californian Colorado : fl. June to August. — Var. a. 

 is the usual Western form ; /3. occurs only in Texas and Eastern 

 Mexico. — Shrub 3-5 feet high, stem 1- l^- inches thick ; joints 2- 



3 lines in diameter ; indistinct tubercles 3-5 lines long ; spines in a. 

 1-2 inches, in /3. 4-6 lines, long. Flower 7-9 lines in diameter. 

 Fruit 5-9 lines long. Seeds few, usually li lines in diameter. 



50. O. TESSELLATA (O. ramosissima, E. in Sill. Journ. 1852) : fru- 

 tescens, erecta seu diffusa, divaricato-ramosissima ; articulis gracili- 

 bus tessellato-tuberculatis csesiis ; tuberculis 5-6 angulatis planis in- 

 ermibus seu aculeum elongatum paucosque minutos gerentibus ; flore 

 purpurascente parva ; bacca setosissima sicca. 



Valley of the Lower Colorado from Sonora to the California moun- 



